72 results on '"Khoo JJ"'
Search Results
2. Lupus nephritis in children in Malaysia
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Khoo, JJ, primary, Pee, S, additional, Thevarajah, B, additional, Yap, YC, additional, and Chin, CK, additional
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- 2005
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3. Seroprevalences and their associated predictors of chikungunya, dengue, Japanese encephalitis and zika among forest fringe dwellers of Peninsular Malaysia.
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Khor CS, Lee HY, Abd-Majid MA, Khoo HY, Khoo JJ, and AbuBakar S
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- Humans, Malaysia epidemiology, Seroepidemiologic Studies, Male, Female, Adult, Young Adult, Middle Aged, Adolescent, Child, Aged, Forests, Immunoglobulin G blood, Child, Preschool, Chikungunya Fever epidemiology, Encephalitis, Japanese epidemiology, Dengue epidemiology, Antibodies, Viral blood, Zika Virus Infection epidemiology
- Abstract
Serological evidence has shown the presence of several mosquito-borne arbovirus infections among the inhabitants of the forest fringe areas of the tropics. Among these infections, Japanese encephalitis, dengue fever, chikungunya fever and Zika fever could be targeted for vaccination to overcome severe infection and limit the disease transmission. Seroprevalence data among this high-risk population are needed to provide an estimate of the potential cost-effectiveness of any vaccine programme targeting these infections. The present study was conducted at six indigenous people (Orang Asli) villages and FELDA (Federal Land Development Authority) settlements located at the forest fringes of Malaysia. All participants consented and provided blood samples and demographic data for the study. The blood samples were tested for the presence of antibodies against CHIKV, DENV, JEV and ZIKV individually using ELISA. Results obtained were also analysed to determine the predictors for CHIKV, DENV, JEV and ZIKV seropositivity. Among the 585 samples tested, 33.0% (N=193), 41.7% (N=244), 10.3% (N=60) and 21.0% (N=123) were positive for CHIKV IgG, DENV IgG, JEV IgG and ZIKV IgG, respectively. Approximately one-third (N=220, 37.6%) of the participants were tested negative for IgG antibodies against all four arboviruses. Age of participants and type of settlement were found to be a significant predictor for CHIKV, DENV, JEV and ZIKV seropositivity. Level of education was a significant predictor for CHIKV, DENV and ZIKV seropositivity. Gender, however, was not found to be a significant predictor for infection with any of these viruses. These findings reaffirmed the significant presence of infection involving these major arboviruses among the group of people living within the forest fringe areas of Peninsular Malaysia. Hence, any future consideration of vaccination for these infections must take into consideration the marginalized and underserved communities living at the forest fringe areas of the tropics where these infections are present.
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- 2024
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4. Establishment and partial characterisation of a new cell line derived from adult tissues of the tsetse fly Glossina morsitans morsitans.
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Bell-Sakyi L, Haines LR, Petrucci G, Beliavskaia A, Hartley C, Khoo JJ, Makepeace BL, Abd-Alla AMM, and Darby AC
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- Animals, Cell Line, Female, RNA, Ribosomal, 16S genetics, Karyotyping, Insect Vectors virology, Tsetse Flies parasitology
- Abstract
Background: Insect cell lines play a vital role in many aspects of research on disease vectors and agricultural pests. The tsetse fly Glossina morsitans morsitans is an important vector of salivarian trypanosomes in sub-Saharan Africa and, as such, is a major constraint on human health and agricultural development in the region., Methods: Here, we report establishment and partial characterisation of a cell line, GMA/LULS61, derived from tissues of adult female G. m. morsitans. GMA/LULS61 cells, grown at 28 °C in L-15 (Leibovitz) medium supplemented with foetal bovine serum and tryptose phosphate broth, have been taken through 23 passages to date and can be split 1:1 at 2-week intervals. Karyotyping at passage 17 revealed a predominantly haploid chromosome complement. Species origin and absence of contaminating bacteria were confirmed by PCR amplification and sequencing of fragments of the COI gene and pan-bacterial 16S rRNA gene respectively. However, PCR screening of RNA extracted from GMA/LULS61 cells confirmed presence of the recently described Glossina morsitans morsitans iflavirus and Glossina morsitans morsitans negevirus, but absence of Glossina pallipides salivary gland hypertrophy virus. GMA/LULS61 cells supported infection and growth of 6/7 different insect-derived strains of the intracellular bacterial symbiont Wolbachia., Conclusions: The GMA/LULS61 cell line has potential for application in a variety of studies investigating the biology of G. m. morsitans and its associated pathogenic and symbiotic microorganisms., (© 2024. The Author(s).)
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- 2024
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5. Microbiome and mitogenomics of the chigger mite Pentidionis agamae: potential role as an Orientia vector and associations with divergent clades of Wolbachia and Borrelia.
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Alkathiry HA, Alghamdi SQ, Sinha A, Margos G, Stekolnikov AA, Alagaili AN, Darby AC, Makepeace BL, and Khoo JJ
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- Animals, DNA, Multilocus Sequence Typing, Orientia, Phylogeny, RNA, Ribosomal, 16S genetics, Rodentia genetics, Saudi Arabia, Borrelia genetics, Microbiota, Orientia tsutsugamushi genetics, Scrub Typhus epidemiology, Scrub Typhus microbiology, Trombiculidae genetics, Trombiculidae microbiology, Wolbachia genetics
- Abstract
Background: Trombiculid mites are globally distributed, highly diverse arachnids that largely lack molecular resources such as whole mitogenomes for the elucidation of taxonomic relationships. Trombiculid larvae (chiggers) parasitise vertebrates and can transmit bacteria (Orientia spp.) responsible for scrub typhus, a zoonotic febrile illness. Orientia tsutsugamushi causes most cases of scrub typhus and is endemic to the Asia-Pacific Region, where it is transmitted by Leptotrombidium spp. chiggers. However, in Dubai, Candidatus Orientia chuto was isolated from a case of scrub typhus and is also known to circulate among rodents in Saudi Arabia and Kenya, although its vectors remain poorly defined. In addition to Orientia, chiggers are often infected with other potential pathogens or arthropod-specific endosymbionts, but their significance for trombiculid biology and public health is unclear., Results: Ten chigger species were collected from rodents in southwestern Saudi Arabia. Chiggers were pooled according to species and screened for Orientia DNA by PCR. Two species (Microtrombicula muhaylensis and Pentidionis agamae) produced positive results for the htrA gene, although Ca. Orientia chuto DNA was confirmed by Sanger sequencing only in P. agamae. Metagenomic sequencing of three pools of P. agamae provided evidence for two other bacterial associates: a spirochaete and a Wolbachia symbiont. Phylogenetic analysis of 16S rRNA and multi-locus sequence typing genes placed the spirochaete in a clade of micromammal-associated Borrelia spp. that are widely-distributed globally with no known vector. For the Wolbachia symbiont, a genome assembly was obtained that allowed phylogenetic localisation in a novel, divergent clade. Cytochrome c oxidase I (COI) barcodes for Saudi Arabian chiggers enabled comparisons with global chigger diversity, revealing several cases of discordance with classical taxonomy. Complete mitogenome assemblies were obtained for the three P. agamae pools and almost 50 SNPs were identified, despite a common geographic origin., Conclusions: P. agamae was identified as a potential vector of Ca. Orientia chuto on the Arabian Peninsula. The detection of an unusual Borrelia sp. and a divergent Wolbachia symbiont in P. agamae indicated links with chigger microbiomes in other parts of the world, while COI barcoding and mitogenomic analyses greatly extended our understanding of inter- and intraspecific relationships in trombiculid mites., (© 2024. The Author(s).)
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- 2024
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6. Multi-Locus Sequence Analysis Indicates Potential Cryptic Speciation in the Chigger Mite Neoschoengastia gallinarum (Hatori, 1920) Parasitising Birds in Asia.
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Rajasegaran P, Koosakulnirand S, Tan KK, Khoo JJ, Suliman Y, Mansor MS, Ahmad Khusaini MKS, AbuBakar S, Chaisiri K, Morand S, Ya'cob Z, and Makepeace BL
- Abstract
Neoschoengastia gallinarum is widely distributed in Asia, preferentially parasitising birds, and heavy infestations have clinical impacts on domestic fowl. In common with other trombiculid mites, the genetic diversity and potential variation in host preferences or pathology induced by N. gallinarum are poorly understood. This study aimed to unravel the geographical variation and population structure of N. gallinarum collected from galliform birds in Peninsular Malaysia and Thailand by inference from concatenated mitochondrial-encoded cytochrome c oxidase subunit I (COI), and nuclear-encoded internal transcribed spacer 2 (ITS2) and 18S ribosomal DNA gene sequences, including a comparison with previously published data from southeastern China. Our multi-locus sequence analysis revealed three monophyletic clades comprising (A) specimens from Peninsular Malaysia, (B) the samples from Thailand together with a minority of Chinese sequences, and (C) the majority of sequences from China. Similarly, most species delimitation approaches divided the specimens into three operational taxonomic units. Analysis of molecular variance revealed 96.41% genetic divergence between Malaysian and Thai populations, further supported by the absence of gene flow (N m = 0.01). In conclusion, despite the two countries sharing a land border, populations of N. gallinarum from Peninsular Malaysia and Thailand appear to be genetically segregated and may represent distinct cryptic species.
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- 2024
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7. Metagenomics of culture isolates and insect tissue illuminate the evolution of Wolbachia , Rickettsia and Bartonella symbionts in Ctenocephalides spp. fleas.
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Beliavskaia A, Tan KK, Sinha A, Husin NA, Lim FS, Loong SK, Bell-Sakyi L, Carlow CKS, AbuBakar S, Darby AC, Makepeace BL, and Khoo JJ
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- Animals, Metagenomics, Insecta, Rickettsia genetics, Bartonella genetics, Siphonaptera microbiology, Ctenocephalides microbiology, Wolbachia genetics
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- 2023
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8. A Multi-landscape Assessment of Leptospira Prevalence on a Diversity of Small Mammals.
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Rosli MZ, Mohd-Taib FS, Khoo JJ, Chee HY, Wong YP, Shafie NJ, Mohamed NZ, AbuBakar S, and Nor SM
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- Animals, Humans, Prevalence, Food, Mammals, Murinae, Leptospira, Refuse Disposal, Leptospirosis epidemiology, Leptospirosis veterinary
- Abstract
Leptospirosis is a major zoonotic disease, especially in the tropics, and rodents were known to be carriers of this bacterium. There was established information on Leptospira prevalence among animal reservoirs in human-dominated landscapes from previous literature. However, there was very little focus given comparing the prevalence of Leptospira in a wide range of habitats. An extensive sampling of small mammals from various landscapes was carried out, covering oil palm plantations, paddy fields, recreational forests, semi-urbans, and wet markets in Peninsular Malaysia. This study aims to determine the prevalence of pathogenic Leptospira in a diversity of small mammals across different landscapes. Cage-trapping was deployed for small mammals' trappings, and the kidneys of captured individuals were extracted, for screening of pathogenic Leptospira by polymerase chain reaction (PCR) using LipL32 primer. Eight microhabitat parameters were measured at each study site. Out of 357 individuals captured, 21 (5.9%) were positive for pathogenic Leptospira of which recreational forest had the highest prevalence (8.8%) for landscape types, whereas Sundamys muelleri shows the highest prevalence (50%) among small mammals' species. Microhabitat analysis reveals that rubbish quantity (p < 0.05) significantly influenced the Leptospira prevalence among small mammals. Furthermore, nMDS analysis indicates that the presence of faeces, food waste, and exposure to humans in each landscape type also were linked with high prevalence of pathogenic Leptospira among the small mammals. This study supplements previous studies on pathogenic Leptospira prevalence across different landscape types, and the major microhabitat factors associated with Leptospira prevalence. This information is crucial for epidemiological surveillance and habitat management to curb the possibility of the disease outbreaks., (© 2023. EcoHealth Alliance.)
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- 2023
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9. Molecular Detection of Candidatus Orientia chuto in Wildlife, Saudi Arabia.
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Alkathiry HA, Alghamdi SQ, Morgan HEJ, Noll ME, Khoo JJ, Alagaili AN, and Makepeace BL
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- Animals, Humans, Animals, Wild, Saudi Arabia epidemiology, Rodentia, Orientia tsutsugamushi genetics, Trombiculidae microbiology, Scrub Typhus diagnosis, Scrub Typhus epidemiology, Scrub Typhus veterinary
- Abstract
Scrub typhus is a zoonosis caused by 3 species of Orientia bacteria, including Candidatus Orientia chuto. This species is known only from a human case in Dubai and infections in wildlife in Kenya. We report molecular detection of Candidatus O. chuto in 2 wild rodent species from Saudi Arabia.
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- 2023
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10. Molecular Surveillance for Vector-Borne Bacteria in Rodents and Tree Shrews of Peninsular Malaysia Oil Palm Plantations.
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Mohd-Azami SNI, Loong SK, Khoo JJ, Husin NA, Lim FS, Mahfodz NH, Ishak SN, Mohd-Taib FS, Makepeace BL, and AbuBakar S
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Many human clinical cases attributed to vector-borne pathogens are underreported in Malaysia, especially in rural localities where healthcare infrastructures are lacking. Here, 217 small mammals, consisting of rodents and tree shrews, were trapped in oil palm plantations in the Peninsular Malaysia states of Johor and Perak. Species identification was performed using morphological and DNA barcoding analyses, and 203 small mammals were included in the detection of selected vector-borne bacteria. The DNA extracted from the spleens was examined for Orientia tsutsugamushi , Borrelia spp., Bartonella spp. and Rickettsia spp. using established PCR assays. The small mammals collected in this study included Rattus tanezumi R3 mitotype ( n = 113), Rattus argentiventer ( n = 24), Rattus tiomanicus ( n = 22), Rattus exulans ( n = 17), Rattus tanezumi sensu stricto ( n = 1) and Tupaia glis ( n = 40). Orientia tsutsugamushi , Borrelia spp. and Bartonella phoceensis were detected in the small mammals with the respective detection rates of 12.3%, 5.9% and 4.9%. Rickettsia spp., however, was not detected. This study encountered the presence of both Lyme disease and relapsing fever-related borreliae in small mammals collected from the oil palm plantation study sites. All three microorganisms ( Orientia tsutsugamushi , Borrelia spp. and Bartonella phoceensis ) were detected in the R. tanezumi R3 mitotype, suggesting that the species is a competent host for multiple microorganisms. Further investigations are warranted to elucidate the relationships between the ectoparasites, the small mammals and the respective pathogens.
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- 2023
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11. Habitat and Season Drive Chigger Mite Diversity and Abundance on Small Mammals in Peninsular Malaysia.
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Alkathiry H, Al-Rofaai A, Ya'cob Z, Cutmore TS, Mohd-Azami SNI, Husin NA, Lim FS, Koosakulnirand S, Mahfodz NH, Ishak SN, Loong SK, Stekolnikov A, Mohd-Taib FS, Abubakar S, Makepeace BL, Chaisiri K, and Khoo JJ
- Abstract
Chigger mites are vectors of the bacterial disease scrub typhus, caused by Orientia spp. The bacterium is vertically transmitted in the vector and horizontally transmitted to terrestrial vertebrates (primarily wild small mammals), with humans as incidental hosts. Previous studies have shown that the size of the chigger populations is correlated with the density of small mammals in scrub typhus-endemic regions. Here, we explore interactions between the small mammals and chiggers in two oil palm plantations located in the Perak and Johor states of Peninsular Malaysia. The location in Perak also contained an aboriginal (Orang Asli) settlement. A ~5% sub-sample from 40,736 chigger specimens was identified from five species of small mammals ( n = 217), revealing 14 chigger species, including two new records for Malaysia. The abundance and species richness of chiggers were significantly affected by habitat type (highest in forest border), state (highest in Perak), and season (highest in dry). The overall prevalence of Orientia tsutsugamushi DNA in small-mammal tissues was 11.7% and was not significantly affected by host or habitat characteristics, but in Johor, was positively associated with infestation by Leptotrombidium arenicola . These findings highlight the risk of contracting scrub typhus in oil palm plantations and associated human settlements., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
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- 2022
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12. Comprehensive approaches for the detection of Burkholderia pseudomallei and diagnosis of melioidosis in human and environmental samples.
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Oslan SNH, Yusoff AH, Mazlan M, Lim SJ, Khoo JJ, Oslan SN, and Ismail A
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- Humans, Multilocus Sequence Typing, Prospective Studies, Virulence Factors genetics, Burkholderia pseudomallei genetics, Melioidosis diagnosis, Melioidosis microbiology
- Abstract
Melioidosis is endemic in Southeast Asia and northern Australia. The causative agent of melioidosis is a Gram-negative bacterium, Burkholderia pseudomallei. Its invasion can be fatal if melioidosis is not treated promptly. It is intrinsically resistant to a variety of antibiotics. In this paper, we present a comprehensive overview of the current trends on melioidosis cases, treatments, B. pseudomallei virulence factors, and molecular techniques to detect the bacterium from different samples. The clinical and microbial diagnosis methods of identification and detection of B. pseudomallei are commonly used for the rapid diagnosis and typing of strains, such as polymerase chain reaction or multi-locus sequence typing. The genotyping strategies and techniques have been constantly evolving to identify genomic loci linked to or associated with this human disease. More research strategies for detecting and controlling melioidosis should be encouraged and conducted to understand the current situation. In conclusion, we review existing diagnostic methodologies for melioidosis detection and provide insights on prospective diagnostic methods for the bacterium., (Copyright © 2022. Published by Elsevier Ltd.)
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- 2022
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13. Visual-spatial dimension integration in digital pathology education enhances anatomical pathology learning.
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Wan KL, Sen A, Selvaratnam L, Naing MIM, Khoo JJ, and Rajadurai P
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- Curriculum, Educational Status, Humans, Learning, Education, Distance methods, Pathology education, Telepathology methods
- Abstract
Literature review demonstrated a surprising lack of publications on digital e-learning pathology resources for senior medical undergraduates and interns. An interactive Digital Pathology Repository (iDPR) integrating two- and three-dimensional (2D, 3D) high-resolution anatomical pathology images with correlated digital histopathology was developed. The novel iDPR was rigorously evaluated using mixed methods to assess pathology knowledge gains (pre- and post-tests), quality impact analysis (questionnaire), user feedback (focus group discussions) and user visual behaviour (eye gaze tracking analysis of 2D/ 3D images).Exposure to iDPR appeared to improve user pathology knowledge, as observed by significantly increased test scores on topic-related quizzes (n = 69, p < 0.001). In addition, most users were highly satisfied with the key design elements of the iDPR tool. Focus group discussion revealed the iDPR was regarded as a relevant online learning resource, although some minor technical issues were also noted. Interestingly, visual behaviour trends indicated that specific diagnostic pathological lesions could be correctly identified faster in 3D images, when compared to 2D images.The iDPR offers promise and potential in pathology education for senior clinical students and interns, gauging from both qualitative and quantitative positive user feedback. With incorporation of image annotations and interactive functionality, and with further technology development, this would prove a useful tool for diagnostic pathology and telepathology. As images with added visual-spatial dimension can provide enhanced detail and aid more rapid diagnosis, future applications of the iDPR could include virtual reality or holographic images of anatomical pathology specimens., (© 2022. The Author(s).)
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- 2022
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14. Leptospirosis among Dengue-Negative Febrile Patients in Selangor, Malaysia.
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Loong SK, Abd-Majid MA, Teoh BT, Cheh MJ, Khor CS, Chao CC, Khoo JJ, and AbuBakar S
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- Humans, Malaysia epidemiology, Antibodies, Bacterial, Immunoglobulin M, Fever diagnosis, Leptospirosis diagnosis, Leptospirosis epidemiology, Leptospira genetics, Dengue diagnosis
- Abstract
In recent years, the number of leptospirosis cases, including the number of deaths, has exponentially increased in Malaysia. From June 2016 to February 2018, blood samples of 321 febrile patients with the presumptive diagnosis of dengue-like illness were examined for possible exposure to Leptospira. Two hundred fifty-five blood samples were tested as negative for dengue. Seminested polymerase chain reaction (PCR) and IgM ELISA for leptospirosis were performed. From the samples, an overall prevalence for leptospirosis based on PCR of 4.7% (12/255) was obtained. Eighteen percent (46/255) were positive for anti-Leptospira IgM antibodies. The genome sequences of six of 12 Leptospira PCR-positive samples showed > 97.0% similarity to Leptospira interrogans. One patient's sample consisted of Leptospira and chikungunya virus, suggesting a coinfection. Findings from the study suggest that leptospirosis is prevalent among dengue-negative febrile patients in Malaysia.
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- 2022
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15. Molecular evidence of rat bocavirus among rodents in Peninsular Malaysia.
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Mohd-Azami SNI, Loong SK, Khoo JJ, Sahimin N, Lim FS, Husin NA, Mahfodz NH, Mohd-Taib FS, Ishak SN, Makepeace BL, and Abubakar S
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- Animals, Malaysia epidemiology, Phylogeny, Rats, Rodentia, Bocavirus genetics
- Abstract
Rat bocavirus (RBoV) and rodent bocavirus (RoBoV) have previously been detected in Rattus norvegicus; however, these viruses have not been reported in rodent populations in Malaysia. We investigated the presence of RBoV and RoBoV in archived rodent specimens. DNA barcoding of the rodent cytochrome c oxidase gene identified five different species: Rattus tanezumi R3 mitotype, Rattus tiomanicus, Rattus exulans, Rattus argentiventer, and Rattus tanezumi sensu stricto. Three spleens were positive for RBoV (1.84%; 3/163), but no RoBoV was detected. Phylogenetic analyzes of the partial non-structural protein 1 gene grouped Malaysian RBoV strains with RBoV strains from China. Further studies among rats from different geographical locations are warranted for this relatively new virus.
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- 2022
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16. New Cell Lines Derived from European Tick Species.
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Bell-Sakyi L, Hartley CS, Khoo JJ, Forth JH, Palomar AM, and Makepeace BL
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Tick cell lines are important tools for research on ticks and the pathogens they transmit. Here, we report the establishment of ten new cell lines from European ticks of the genera Argas , Dermacentor , Hyalomma , Ixodes and Rhipicephalus originating from Germany and Spain. For each cell line, the method used to generate the primary culture, a morphological description of the cells and species confirmation by sequencing of the partial 16S rRNA gene are presented. Further molecular analysis of the two new Ixodes ricinus cell lines and three existing cell lines of the same species revealed genetic variation between cell lines derived from ticks collected in the same or nearby locations. Collectively, these new cell lines will support research into a wide range of viral, bacterial and protozoal tick-borne diseases prevalent in Europe.
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- 2022
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17. Multiyear prospective cohort study to evaluate the risk potential of MERS-CoV infection among Malaysian Hajj pilgrims (MERCURIAL): a study protocol.
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Johari J, Hontz RD, Pike BL, Husain T, Chong CK, Rusli N, Sulaiman LH, Verasahib K, Mohd Zain R, Azman AS, Khor CS, Nor'e SS, Tiong V, Lee HY, Teoh BT, Sam SS, Khoo JJ, Abd Jamil J, Loong SK, Yaacob CN, Mahfodz NH, Azizan NS, Che Mat Seri NAA, Mohd-Rahim NF, Hassan H, Yahaya H, Garcia-Rivera JA, and AbuBakar S
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- Humans, Islam, Middle East epidemiology, Prospective Studies, Saudi Arabia epidemiology, Travel, Coronavirus Infections epidemiology, Coronavirus Infections prevention & control, Middle East Respiratory Syndrome Coronavirus
- Abstract
Introduction: Middle East respiratory syndrome (MERS) is a viral respiratory infection caused by the MERS-CoV. MERS was first reported in the Kingdom of Saudi Arabia in 2012. Every year, the Hajj pilgrimage to Mecca attracts more than two million pilgrims from 184 countries, making it one of the largest annual religious mass gatherings (MGs) worldwide. MGs in confined areas with a high number of pilgrims' movements worldwide continues to elicit significant global public health concerns. MERCURIAL was designed by adopting a seroconversion surveillance approach to provide multiyear evidence of MG-associated MERS-CoV seroconversion among the Malaysian Hajj pilgrims., Methods and Analysis: MERCURIAL is an ongoing multiyear prospective cohort study. Every year, for the next 5 years, a cohort of 1000 Hajj pilgrims was enrolled beginning in the 2016 Hajj pilgrimage season. Pre-Hajj and post-Hajj serum samples were obtained and serologically analysed for evidence of MERS-CoV seroconversion. Sociodemographic data, underlying medical conditions, symptoms experienced during Hajj pilgrimage, and exposure to camel and untreated camel products were recorded using structured pre-Hajj and post-Hajj questionnaires. The possible risk factors associated with the seroconversion data were analysed using univariate and multivariate logistic regression. The primary outcome of this study is to better enhance our understanding of the potential threat of MERS-CoV spreading through MG beyond the Middle East., Ethics and Dissemination: This study has obtained ethical approval from the Medical Research and Ethics Committee (MREC), Ministry of Health Malaysia. Results from the study will be submitted for publication in peer-reviewed journals and presented in conferences and scientific meetings., Trial Registration Number: NMRR-15-1640-25391., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
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- 2021
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18. Rhipicephalus Tick: A Contextual Review for Southeast Asia.
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Tan LP, Hamdan RH, Hassan BNH, Reduan MFH, Okene IA, Loong SK, Khoo JJ, Samsuddin AS, and Lee SH
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Rhipicephalus species are distributed globally with a notifiable presence in Southeast Asia (SEA) within animal and human populations. The Rhipicephalus species are highly adaptive and have established successful coexistence within human dwellings and are known to be active all year round, predominantly in tropical and subtropical climates existing in SEA. In this review, the morphological characteristics, epidemiology, and epizootiology of Rhipicephalus tick species found in SEA are reviewed. There are six commonly reported Rhipicephalus ticks in the SEA region. Their interactions with their host species that range from cattle, sheep, and goats, through cats and dogs, to rodents and man are discussed in this article. Rhipicephalus -borne pathogens, including Anaplasma species, Ehrlichia species, Babesia species, and Theileria species, have been highlighted as are relevant to the region in review. Pathogens transmitted from Rhipicepahalus ticks to host animals are usually presented clinically with signs of anemia, jaundice, and other signs of hemolytic changes. Rhipicephalus ticks infestation also account for ectoparasitic nuisance in man and animals. These issues are discussed with specific interest to the SEA countries highlighting peculiarities of the region in the epidemiology of Rhipicephalus species and attendant pathogens therein. This paper also discusses the current general control strategies for ticks in SEA proffering measures required for increased documentation. The potential risks associated with rampant and improper acaricide use are highlighted. Furthermore, such practices lead to acaricide resistance among Rhipicephalus species are highlighted.
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- 2021
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19. Replication Kinetics of Rickettsia raoultii in Tick Cell Lines.
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Husin NA, Khoo JJ, Zulkifli MMS, Bell-Sakyi L, and AbuBakar S
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Rickettsia raoultii is one of the causative agents of tick-borne lymphadenopathy in humans. This bacterium was previously isolated and propagated in tick cell lines; however, the growth characteristics have not been investigated. Here, we present the replication kinetics of R. raoultii in cell lines derived from different tick genera (BME/CTVM23, RSE/PILS35, and IDE8). Tick cell cultures were infected in duplicate with cryopreserved R. raoultii prepared from homologous cell lines. By 12-14 days post infection, 100% of the cells were infected, as visualized in Giemsa-stained cytocentrifuge smears. R. raoultii growth curves, determined by rickettsiae-specific gltA qPCR, exhibited lag, exponential, stationary and death phases. Exponential phases of 4-12 days and generation times of 0.9-2.6 days were observed. R. raoultii in BME/CTVM23 and RSE/PILS35 cultures showed, respectively, 39.5- and 37.1-fold increases compared to the inoculum. In contrast, multiplication of R. raoultii in the IDE8 cultures was 110.1-fold greater than the inoculum with a 7-day stationary phase. These findings suggest variation in the growth kinetics of R. raoultii in the different tick cell lines tested, amongst which IDE8 cells could tolerate the highest levels of R. raoultii replication. Further studies of R. raoultii are needed for a better understanding of its persistence within tick populations.
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- 2021
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20. Current tools for the diagnosis and detection of spotted fever group Rickettsia.
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Husin NA, AbuBakar S, and Khoo JJ
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- Animals, Humans, Serologic Tests, Spotted Fever Group Rickettsiosis immunology, Spotted Fever Group Rickettsiosis diagnosis
- Abstract
Spotted fever group (SFG) rickettsiae causes a number of diseases in humans worldwide, which can range from mild to highly lethal. Since the clinical presentations of rickettsioses caused by SFG rickettsiae are variable and may be similar to the diseases caused by other rickettsiae, such as Orientia tsutsugamushi (agent for scrub typhus), Coxiella burnetii (agent for Q fever) and the typhus group rickettsiae (agents for epidemic and murine typhus), the accurate diagnosis of infections caused by SFG Rickettsia remains challenging especially in resource-poor settings in developing countries. This review summarizes the various diagnostic and detection tools that are currently available for the confirmation of infections by SFG rickettsiae. The advantages and challenges pertaining to the different serological and molecular detections methods, as well as new assays in development, are discussed. The utility of the detection tools contributing to the surveillance of SFG rickettsiae in arthropods and animals are reviewed., (Copyright © 2021. Published by Elsevier B.V.)
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- 2021
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21. Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice.
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Tiong V, Loong SK, Mohamad Wali HA, Tan KK, Jee PF, Lim FS, Khoo JJ, Wong PF, Chang LY, and Abubakar S
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- Animals, Laboratories, Mice, Mice, Inbred BALB C, RNA, Ribosomal, 16S genetics, Streptococcus, Encephalitozoon cuniculi genetics, Encephalitozoonosis veterinary
- Abstract
Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.
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- 2021
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22. Molecular detection of pathogens from ectoparasites recovered from peri-domestic animals, and the first description of a Candidatus Midichloria sp. from Haemaphysalis wellingtoni from rural communities in Malaysia.
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Khoo JJ, Husin NA, Lim FS, Oslan SNH, Mohd Azami SNI, To SW, Abd Majid MA, Lee HY, Loong SK, Khor CS, and AbuBakar S
- Subjects
- Anaplasma isolation & purification, Animals, Borrelia isolation & purification, Cats microbiology, Cats parasitology, Chickens microbiology, Chickens parasitology, Coxiella burnetii isolation & purification, Dogs microbiology, Dogs parasitology, Malaysia, Polymerase Chain Reaction veterinary, Rickettsiales genetics, Rural Population, Sequence Analysis, DNA veterinary, Ctenocephalides microbiology, Ctenocephalides parasitology, Ixodidae microbiology, Ixodidae parasitology, Rickettsiales isolation & purification
- Abstract
Rural communities in Malaysia have been shown to be exposed to Coxiella, Borrelia and rickettsial infections in previous seroprevalence studies. Further research is necessary to identify the actual causative agents and the potential vectors of these infections. The arthropods parasitizing peri-domestic animals in these communities may serve as the vector in transmitting arthropod-borne and zoonotic agents to the humans. Molecular screening of bacterial and zoonotic pathogens from ticks and fleas collected from dogs, cats and chickens from six rural communities in Malaysia was undertaken. These communities were made up of mainly the indigenous people of Malaysia, known as the Orang Asli, as well as settlers in oil palm plantations. The presence of Coxiella burnetii, Borrelia, and rickettsial agents, including Rickettsia and Anaplasma, was investigated by performing polymerase chain reaction (PCR) and DNA sequencing. Candidatus Rickettsia senegalensis was detected in one out of eight pools of Ctenocephalides felis fleas. A relapsing fever group Borrelia sp. was identified from one of seven Haemaphysalis hystricis ticks tested. The results from the PCR screening for Anaplasma unexpectedly revealed the presence of Candidatus Midichloria sp., a potential tick endosymbiont, in two out of fourteen Haemaphysalis wellingtoni ticks tested. C. burnetii was not detected in any of the samples tested. The findings here provide evidence for the presence of potentially novel strains of rickettsial and borrelial agents in which their impact on public health risks among the rural communities in Malaysia merit further investigation. The detection of a potential endosymbiont of ticks also suggest that the presence of tick endosymbionts in the region is not fully explored., (Copyright © 2020 Elsevier B.V. All rights reserved.)
- Published
- 2021
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23. Bacterial profiling of head lice isolated from the Orang Asli: A first report in Malaysia.
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Abd Majid MA, Khoo JJ, Lim FS, Khor CS, Loong SK, Low VL, Lee HY, and AbuBakar S
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- Animals, Bacteria isolation & purification, Child, DNA, Bacterial genetics, Ethnicity, Female, Humans, Lice Infestations, Malaysia, Male, Microbiota, Phylogeny, RNA, Ribosomal, 16S genetics, Bacteria classification, Pediculus microbiology
- Abstract
This study was carried out to determine from bacterial profiling to the bacterial profiles of head lice among the Orang Asli communities. The head lice were collected from Orang Asli community volunteers. The surface sterilized head lice pools were subjected to genomic DNA extraction while next generation sequencing of the 16S rRNA gene was performed using the Illumina MiSeq platform. Six female and three male head lice identified as Pediculus humanus capitis were collected. A total of 111 368 number of NGS sequencing reads were recorded while another 223 bacterial taxa sequences were obtained. Symbiotic bacteria showed the highest number of reads, with Arsenophonus and Rhodococcus sequences being the most abundant genera in the female and male samples, respectively. The female head lice contained a more distinct microbial diversity. Amongst the pathogenic bacterial species sequences noted were the methicillin-resistant Staphylococcus aureus, Streptobacillus moniliformis, Haemophilus influenzae, Bordetella pertussis and Acinetobacter baumannii. The 16S rRNA genome sequencing revealed a number of rare and pathogenic bacterial species within the head lice of the Orang Asli. The socio-economic practices of the community which involved forest foraging and hunting, and their poor living conditions potentially facilitated the transmission of zoonotic bacterial pathogens, including those found within the head lice. Hence, there is the possibility that the head lice could serve as vectors for the transmission of pathogenic bacteria. This study highlighted the diverse microbial community found within the head lice's gut of the Orang Asli, with the detection of multiple rare and pathogenic bacteria capable of causing severe infections.
- Published
- 2020
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24. Culturable pathogenic bacteria in ticks parasitizing farm animals and rodents in Malaysia.
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Loong SK, Lim FS, Khoo JJ, Lee HY, Suntharalingam C, Ishak SN, Mohd-Taib FS, and AbuBakar S
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- Animals, Bacteria isolation & purification, Cattle parasitology, Female, Goats parasitology, Malaysia, Male, Animals, Domestic parasitology, Bacteria classification, Rodentia parasitology, Ticks microbiology
- Abstract
Ticks are vectors of bacteria, protozoa and viruses capable of causing serious and life threatening diseases in humans and animals. Disease transmission occurs through the transfer of pathogen from tick bites to susceptible humans or animals. Most commonly known tick-borne pathogens are obligate intracellular microorganisms but little is known on the prevalence of culturable pathogenic bacteria from ticks capable of growth on artificial nutrient media. One hundred and forty seven ticks originating from dairy cattle, goats and rodents were collected from nine selected sites in Peninsular Malaysia. The culture of surfacesterilized tick homogenates revealed the isolation of various pathogenic bacteria including, Staphylococcus sp., Corynebacterium sp., Rothia sp., Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli and Bacillus sp. and its derived genera. These pathogens are among those that affect humans and animals. Findings from this study suggest that in addition to the regular intracellular pathogens, ticks could also harbor extracellular pathogenic bacteria. Further studies, hence, would be needed to determine if these extracellular pathogens could contribute to human or animal infection.
- Published
- 2020
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25. Severe Symptomatic Hypophosphataemia as a Complication of Parenteral Iron Replacement.
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Teh KK, Chuah MB, Tay SW, Lim AY, and Khoo JJ
- Abstract
Parental iron replacement is given to patients with severe iron deficiency or intolerance to oral iron. Hypophosphataemia has been reported to occur as a complication of parental iron replacement, and is postulated to be related to the carbohydrate moieties used in the parenteral preparations. Hypophosphataemia is under-diagnosed as symptoms such as fatigue, muscle weakness and poor effort tolerance mimic anaemia. Severe hypophosphataemia (<0.32 mmol/l) can result in significant complications such as confusion, rhabdomyolysis and arrhythmias. We report a patient with recurrent admissions for non-specific symptoms attributed to iron deficiency anaemia who received multiple doses of parenteral ferric carboxymaltose (FCM). He was found to have severe hypophosphataemia, with further evaluation showing increased renal phosphate wasting and elevated serum levels of fibroblast-growth-factor 23 (FGF23). FCM was stopped and he was given high-dose oral iron supplementation, with no further episodes of hypophosphataemia., Learning Points: The carbohydrate moieties used in parenteral iron preparations are different, and may have a dose-dependent relationship with the development of hypophosphataemia.The mechanism by which hypophosphataemia occurs after parenteral iron replacement is related to increased serum levels of FGF23, which increases renal phosphate wasting.The serum phosphate levels of patients receiving parenteral iron replacement (especially ferric carboxymaltose or iron polymaltose) should be routinely monitored for hypophosphataemia, which is an under-diagnosed complication., Competing Interests: Conflicts of Interests: The Authors declare that there are no competing interests., (© EFIM 2020.)
- Published
- 2020
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26. Serological evidence of DENV, JEV, and ZIKV among the indigenous people (Orang Asli) of Peninsular Malaysia.
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Khor CS, Mohd-Rahim NF, Hassan H, Tan KK, Zainal N, Teoh BT, Sam SS, Khoo JJ, Lee HY, Lim YA, and Abubakar S
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- Adult, Antibodies, Neutralizing blood, Cross Reactions, Dengue Virus immunology, Encephalitis Virus, Japanese immunology, Enzyme-Linked Immunosorbent Assay, Female, Humans, Immunoglobulin G blood, Malaysia epidemiology, Male, Seroepidemiologic Studies, Young Adult, Zika Virus immunology, Antibodies, Viral blood, Dengue epidemiology, Encephalitis, Japanese epidemiology, Flavivirus immunology, Indigenous Peoples, Zika Virus Infection epidemiology
- Abstract
Dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV) are mosquito-borne flavivirus of medical importance in tropical countries such as Malaysia. However, much remains unknown regarding their prevalence among the underserved indigenous people (Orang Asli) living in communities in the forest fringe areas of Peninsular Malaysia. Information on the prevalence of diseases is necessary to elevate the effectiveness of disease control and preventive measures. This study aimed to determine the seroprevalence of the three major flaviviruses among the Orang Asli and investigate the association between demographic factors and seropositivities. Sampling activities were conducted in the Orang Asli villages to obtain serum samples and demographic data from consenting volunteers. The presence of DENV, JEV, and ZIKV immunoglobulin G (IgG) antibodies in the sera were examined using commercial enzyme-linked immunosorbent assay kits. A focus reduction neutralization assay was performed to measure virus-specific neutralizing antibodies. A total of 872 serum samples were obtained from the Orang Asli volunteers. Serological assay results revealed that DENV IgG, JEV IgG, and ZIKV IgG seropositivities among the Orang Asli were at 4.9%, 48.4%, and 13.2%, respectively. Neutralizing antibodies (FRNT50 ≥ 1:40) against JEV and ZIKV were found in 86.7% and 100.0%, respectively, out of the samples tested. Positive serology to all three viruses corresponded significantly to the age of the volunteers with increasing seropositivity in older volunteers. Findings from the study suggest that Orang Asli are at significant risk of contracting JEV and ZIKV infections despite the lack of active transmission of the viruses in the country., (© 2019 Wiley Periodicals, Inc.)
- Published
- 2020
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27. Isolation and Propagation of Laboratory Strains and a Novel Flea-Derived Field Strain of Wolbachia in Tick Cell Lines.
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Khoo JJ, Kurtti TJ, Husin NA, Beliavskaia A, Lim FS, Zulkifli MMS, Al-Khafaji AM, Hartley C, Darby AC, Hughes GL, AbuBakar S, Makepeace BL, and Bell-Sakyi L
- Abstract
Wolbachia are intracellular endosymbionts of several invertebrate taxa, including insects and nematodes. Although Wolbachia DNA has been detected in ticks, its presence is generally associated with parasitism by insects. To determine whether or not Wolbachia can infect and grow in tick cells, cell lines from three tick species, Ixodes scapularis , Ixodes ricinus and Rhipicephalus microplus , were inoculated with Wolbachia strains w Stri and w AlbB isolated from mosquito cell lines. Homogenates prepared from fleas collected from cats in Malaysia were inoculated into an I. scapularis cell line. Bacterial growth and identity were monitored by microscopy and PCR amplification and sequencing of fragments of Wolbachia genes. The w Stri strain infected Ixodes spp. cells and was maintained through 29 passages. The w AlbB strain successfully infected Ixodes spp. and R. microplus cells and was maintained through 2-5 passages. A novel strain of Wolbachia belonging to the supergroup F, designated w CfeF, was isolated in I. scapularis cells from a pool of Ctenocephalides sp. cat fleas and maintained in vitro through two passages over nine months. This is the first confirmed isolation of a Wolbachia strain from a flea and the first isolation of any Wolbachia strain outside the "pandemic" A and B supergroups. The study demonstrates that tick cells can host multiple Wolbachia strains, and can be added to panels of insect cell lines to improve success rates in isolation of field strains of Wolbachia .
- Published
- 2020
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28. Bacterial communities in Haemaphysalis, Dermacentor and Amblyomma ticks collected from wild boar of an Orang Asli Community in Malaysia.
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Lim FS, Khoo JJ, Tan KK, Zainal N, Loong SK, Khor CS, and AbuBakar S
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- Animals, Bacteria classification, Bacterial Infections epidemiology, Bacterial Infections microbiology, Malaysia epidemiology, Microbiota, Prevalence, RNA, Bacterial analysis, RNA, Ribosomal, 16S analysis, Species Specificity, Sus scrofa, Swine, Swine Diseases microbiology, Swine Diseases parasitology, Bacteria isolation & purification, Bacterial Infections veterinary, Ixodidae classification, Ixodidae microbiology, Ixodidae physiology, Swine Diseases epidemiology, Tick Infestations epidemiology
- Abstract
Ticks are hematophagous vectors of arthropod-borne disease agents globally. In Malaysia, despite seroprevalence studies indicating the presence of tick-borne diseases among the indigenous people, the etiological agents of these diseases are still unclear. These indigenous people, also known as the Orang Asli, still live in forested areas with frequent contact with wildlife. Wild boar are ubiquitously found in the forested areas where the Orang Asli communities are located and are commonly hunted as a food supplement. In this study, we aim to determine the tick species parasitizing wild boar from an Orang Asli community, and explore the tick-associated bacterial communities using 16 s rRNA amplicon sequencing on the Ion Torrent PGM™ platform. A total of 72 ticks were collected from three wild boar and were morphologically identified as Haemaphysalis hystricis (n = 32), Dermacentor compactus (n = 15), Amblyomma testudinarium (n = 13), Dermacentor steini (n = 10) and Dermacentor atrosignatus (n = 2). Across all tick samples, 910 bacterial taxa were identified. Although the bacterial communities were not significantly distinct between tick species in beta-diversity analyses, Coxiella, Rickettsia and Francisella were detected at high relative abundance in H. hystricis, D. compactus and D. steini respectively. Many other bacterial genera, including those that have been described in many different tick species, were also identified, including Pseudomonas, Acinetobacter, Staphylococcus and Corynebacterium. Beta-diversity analyses also showed that the bacterial communities were separated based on the animal host from which the ticks were collected from, suggesting that the bacterial communities here may be influenced by the animal skin microflora, host blood or the environment. PCR screening confirmed the presence of Rickettsia sp. related to spotted fever group Rickettsia in some of the ticks. This study provides baseline knowledge of the microbiome of H. hystricis, D. atrosignatus, D. compactus, D. steini and A. testudinarium parasitizing wild boar in this region. The information gained in this study provides the basis to target our efforts in H. hystricis, D. compactus and D. steini for the future investigation of vector competence and the zoonotic potential for the Coxiella, Rickettsia and Francisella detected here, as well as their implications for the risks of tick-borne diseases among the Orang Asli communities., (Copyright © 2019 Elsevier GmbH. All rights reserved.)
- Published
- 2020
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29. An overview of rickettsiae in Southeast Asia: Vector-animal-human interface.
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Low VL, Tan TK, Khoo JJ, Lim FS, and AbuBakar S
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- Animals, Asia, Southeastern epidemiology, Disease Vectors, Humans, Rickettsia genetics, Zoonoses, Rickettsia classification, Rickettsia Infections epidemiology, Rickettsia Infections microbiology
- Abstract
Rickettsioses are emerging, and re-emerging diseases caused by obligate intracellular arthropod-borne bacteria that infect humans and animals worldwide. Various rickettsiae such as Orientia, Rickettsia, Anaplasma and Ehrlichia have been circulated in companion, domesticated and wild animals through bites of infected ticks, fleas, lice or mites. This review summarizes the infections of rickettsiae, including the newly discovered regional species Rickettsia thailandii, Candidatus Rickettsia sepangensis, Candidatus Rickettsia johorensis, Candidatus Rickettsia laoensis, Candidatus Rickettsia mahosotii, Candidatus Rickettsia khammouanensis, Candidatus Anaplasma pangolinii, and other novel genotypes in vectors, humans and animals in Southeast Asia. Issues on some unidentified rickettsiae that elicit immune responses and production of antibodies that are cross-reactive with the antigens used are discussed. Knowledge gaps which required attention are also identified in this review., (Copyright © 2019 Elsevier B.V. All rights reserved.)
- Published
- 2020
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30. pSTAT3 and MYC in Epstein-Barr virus-positive diffuse large B-cell lymphoma.
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Teoh SH, Khoo JJ, Abdul Salam DSD, Peh SC, and Cheah SC
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- Adult, Aged, Aged, 80 and over, Female, Humans, Immunohistochemistry methods, Janus Kinase 1 metabolism, Malaysia, Male, Middle Aged, Prognosis, STAT3 Transcription Factor metabolism, Epstein-Barr Virus Infections virology, Herpesvirus 4, Human pathogenicity, Lymphoma, Large B-Cell, Diffuse pathology, Lymphoma, Large B-Cell, Diffuse virology
- Abstract
Introduction: Epstein-Barr Virus (EBV) is associated with several B-cell non-Hodgkin's lymphoma (NHL), but the role of EBV in diffuse large B-cell lymphoma (DLBCL) is poorly defined. Several studies indicated the expression of phosphorylated STAT3 (pSTAT3) is predominant in EBV(+)- DLBCL, of which its activated form can promote the downstream oncogenes expression such as c-MYC. c-MYC gene rearrangements are frequently found in aggressive lymphoma with inferior prognosis. Furthermore, EBV is a co-factor of MYC dysregulation. JAK1/STAT3 could be the downstream pathway of EBV and deregulates MYC. To confirm the involvement of EBV in JAK1/ STAT3 activation and MYC deregulation, association of EBV, pSTAT3 and MYC in EBV(+)- DLBCL cases were studied. The presence of pSTAT3 and its upstream proteins: pJAK1 is identify to delineate the role of EBV in JAK1/STAT3 pathway., Materials and Methods: 51 cases of DLBCL paraffin-embedded tissue samples were retrieved from a single private hospital in Kuala Lumpur, Malaysia. EBER-ISH was performed to identify the EBV expression; ten EBV(+)-DLBCL cases subjected to immunohistochemistry for LMP1, pJAK1, pSTAT3 and MYC; FISH assay for c-MYC gene rearrangement., Results: Among 10 cases of EBV(+)-DLBCL, 90% were non-GCB subtype (p=0.011), 88.9% expressed LMP1. 40% EBV(+)-DLBCL had pJAK1 expression., Conclusion: 66.7% EBV(+)-DLBCL showed the positivity of pSTAT3, which implies the involvement of EBV in constitutive JAK/STAT pathway. 44.5% EBV(+)-DLBCL have co-expression of pSTAT3 and MYC, but all EBV(+)-DLBCL was absence with c-MYC gene rearrangement. The finding of clinical samples might shed lights to the lymphomagenesis of EBV associated with non-GCB subtypes, and the potential therapy for pSTAT3-mediated pathway.
- Published
- 2019
31. Acute oral toxicity of the ellagitannin geraniin and a geraniin-enriched extract from Nephelium lappaceum L rind in Sprague Dawley rats.
- Author
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Moorthy M, Khoo JJ, and Palanisamy UD
- Abstract
Despite the lack of its toxicity evaluation, traditional herbal products are being widely used for various health indications. Geraniin, an ellagitannin, is a bioactive compound found in many traditional herbal medicines. In spite its numerous health benefits ranging from anti-inflammatory, anti-hyperglycaemic, hepatoprotective, anti-cancer and anti-microbial, no toxicity data on geraniin is available. The objective of this study is to evaluate the acute oral toxicity of geraniin and an enriched geraniin-extract of Nephelium lappaceum L rind. This study followed the guidelines of the OECD 423 acute oral toxicity test. Subsequent to a single oral administration of the test compounds, the rats were observed for 14 days for signs of toxicity and mortality. Following euthanasia, full blood count, biochemistry of blood and histopathology assessment of organs were carried out. All parameters analysed indicated insignificant difference compared to control. The LD
50 cut-off values for both geraniin and geraniin-enriched extract was established to be 2000 mg/kg b. w., following a single oral dose. It was however observed that the hepatocytes of three geraniin-administered rats exhibited a 'foamy appearance'. As such, the no-observed-adverse-effect level of geraniin is below 2000 mg/kg, while that of geraniin-enriched extract is up to 2000 mg/kg. Further detailed toxicity studies are required to establish geraniin or its enriched extract from Nephelium lappaceum L rind safe for human consumption.- Published
- 2019
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32. Seroprevalence of Borrelia burgdorferi among the indigenous people (Orang Asli) of Peninsular Malaysia.
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Khor CS, Hassan H, Mohd-Rahim NF, Chandren JR, Nore SS, Johari J, Loong SK, Abd-Jamil J, Khoo JJ, Lee HY, Pike BL, Li-Ping W, Lim YA, and AbuBakar S
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Child, Child, Preschool, Enzyme-Linked Immunosorbent Assay, Female, Humans, Malaysia epidemiology, Male, Middle Aged, Seroepidemiologic Studies, Young Adult, Borrelia burgdorferi, Indigenous Peoples, Lyme Disease epidemiology
- Abstract
Introduction: Lyme disease has been well-described in the North America and European countries. However, information is still very limited in the developing countries including Malaysia. The Orang Asli (OA), the indigenous people of Peninsular Malaysia reside mostly in the forest and forest fringe areas abundant with the vector for Lyme disease. Here, we described the seroprevalence of Borellia burgdorferi (B. burgdorferi) among the OA and demographic variables that could be associated with seroprevalence., Methodology: A total of 16 OA villages distributed across 8 states in Peninsular Malaysia participated in this study. Sera obtained from 904 OA volunteers were screened for anti-B. burgdorferi IgG antibodies. ELISA results obtained and demographic information collected were analysed to identify possible variables associated with seroprevalence., Results: A total of 73 (8.1%) OA tested positive for anti-B. burgdorferi IgG antibodies. Among all the variables examined, village of residence (p = 0.045) was the only significant predictor for seropositivity. High (> 10.0%) prevalence was associated with three OA villages. Those living in one particular village were 1.65 times more likely to be seropositive as compared to other OA villages. Age, gender, marital status, household size, level of education, monthly household income and occupation were not significant predictors for seropositivity., Conclusion: Results of the present study support earlier findings that B. burgdorferi infection among Malaysians is currently under-recognized. Further studies will be needed at these locations to confirm the presence of Lyme disease among these populations., Competing Interests: No Conflict of Interest is declared, (Copyright (c) 2019 Sazaly AbuBakar, Chee-Sieng Khor, Habibi Hassan, Nurul-Farhana Mohd-Rahim, Josephine-Rebecca Chandren, Siti-Sarah Nore, Jefree Johari, Shih-Keng Loong, Juraina Abd-Jamil, Jing-Jing Khoo, Hai-Yen Lee, Brian L Pike, Li-Ping Wong, Yvonne Ai-Lian Lim.)
- Published
- 2019
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33. Efficacy of geraniin on dengue virus type-2 infected BALB/c mice.
- Author
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Abdul Ahmad SA, Palanisamy UD, Khoo JJ, Dhanoa A, and Syed Hassan S
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- Animals, Cell Line, Chlorocebus aethiops, Dengue Virus physiology, Fruit chemistry, Liver drug effects, Liver pathology, Liver virology, Male, Mice, Mice, Inbred BALB C, Polymerase Chain Reaction, RNA, Viral blood, RNA, Viral genetics, Sapindaceae chemistry, Vero Cells, Viral Load, Antiviral Agents pharmacology, Dengue drug therapy, Dengue Virus drug effects, Glucosides pharmacology, Hydrolyzable Tannins pharmacology, Virus Replication drug effects
- Abstract
Background: Dengue continues to be a major international public health concern. Despite that, there is no clinically approved antiviral for treatment of dengue virus (DENV) infections. In this study, geraniin extracted from the rind of Nephelium lappaceum was shown to inhibit the replication of DENV-2 in both in vitro and in vivo experiments., Methods: The effect of geraniin on DENV-2 RNA synthesis in infected Vero cells was tested using quantitative RT-PCR. The in vivo efficacy of geraniin in inhibiting DENV-2 infection was then tested using BALB/c mice with geraniin administered at three different times. The differences in spleen to body weight ratio, DENV-2 RNA load and liver damage between the three treatment groups as compared to DENV-2 infected mice without geraniin administration were determined on day eight post-infection., Results: Quantitative RT-PCR confirmed the decrease in viral RNA synthesis of infected Vero cells when treated with geraniin. Geraniin seemed to provide a protective effect on infected BALB/c mice liver when given at 24 h pre- and 24 h post-infection as liver damage was observed to be very mild even though a significant reduction of DENV-2 RNA load in serum was not observed in these two treatment groups. However, when administered at 72 h post-infection, severe liver damage in the form of necrosis and haemorrhage had prevailed despite a substantial reduction of DENV-2 RNA load in serum., Conclusions: Geraniin was found to be effective in reducing DENV-2 RNA load when administered at 72 h post-infection while earlier administration could prevent severe liver damage caused by DENV-2 infection. These results provide evidence that geraniin is a potential candidate for the development of anti-dengue drug.
- Published
- 2019
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34. Detection of a Borrelia sp. From Ixodes granulatus Ticks Collected From Rodents in Malaysia.
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Khoo JJ, Ishak SN, Lim FS, Mohd-Taib FS, Khor CS, Loong SK, and AbuBakar S
- Subjects
- Animals, Borrelia genetics, Female, Malaysia, Male, Borrelia isolation & purification, Ixodes microbiology, Rodentia parasitology
- Abstract
The Borrelia genus consists of spirochete bacteria known to cause Lyme disease (LD) and relapsing fever in humans. Borrelia pathogens are commonly transmitted via arthropod vectors such as ticks, mites, or lice. Here, we report the molecular screening of LD group Borrelia sp. from ticks (Acari: Ixodidae) collected from rodents trapped in recreational forests and a semiurban residential area in the Selangor state in Malaysia. Of 156 adult ticks surveyed, 72 ticks were determined as positive for Borrelia sp. by polymerase chain reaction (PCR). All Borrelia PCR-positive ticks belonged to the Ixodes granulatus Supino species. Borrelia sp. was not detected in other tick species examined, including Dermacentor sp. and Amblyomma sp. ticks. Thirteen Borrelia PCR-positive tick samples were selected for further sequence analyses. Phylogenetic analyses of partial flaB gene sequences revealed that the Borrelia sp. were closely related to the LD group borreliae, Borrelia yangtzensis; a novel Borrelia genospecies reported in East Asian countries including Japan, Taiwan, and China. To our knowledge, this is the first report of Borrelia sp. related to Borrelia yangtzensis detected in Malaysia and Southeast Asia. The zoonotic potential of the Borrelia sp. reported here merits further investigation, as it may explain the previously reported serological evidence for borrelial infections in Malaysia.
- Published
- 2018
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35. Seroprevalence of Q Fever Among the Indigenous People (Orang Asli) of Peninsular Malaysia.
- Author
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Khor CS, Mohd-Rahim NF, Hassan H, Chandren JR, Nore SS, Johari J, Loong SK, Abd-Jamil J, Khoo JJ, Lee HY, Pike BL, Wong LP, Lim YA, Zandi K, and AbuBakar S
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Child, Child, Preschool, Ethnicity, Female, Humans, Malaysia epidemiology, Male, Middle Aged, Q Fever blood, Risk Factors, Seroepidemiologic Studies, Antibodies, Bacterial blood, Coxiella burnetii immunology, Q Fever epidemiology
- Abstract
Q fever is a disease caused by Coxiella burnetii. It is a disease of public health concern in many parts of the world. In this study, we described the seroprevalence of Q fever among selected populations of Orang Asli (OA), indigenous people, many of whom live within the forest fringe areas of Peninsular Malaysia. Serum samples were obtained from 887 OA participants from selected villages. Samples were analyzed for the presence of IgG antibodies reactive against C. burnetii by enzyme-linked immunosorbent assay. Statistical methods were used to identify possible associations between seropositivity for C. burnetii and a number of demographic variables obtained from the questionnaires. In total, 9.6% (n = 85/887) of the serum samples were reactive to C. burnetii. Statistical results suggest that elderly male OA residing in OA village, Bukit Payung, were most likely to be tested seropositive for C. burnetii. This study suggests that OA are at a significant risk of contracting C. burnetii infection, and both demographic and geographic factors are important contributors to this risk. Further prospective studies are needed to establish the true burden of C. burnetii infection within the indigenous population as well as within Peninsular Malaysia as a whole.
- Published
- 2018
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36. Automated quantification of renal interstitial fibrosis for computer-aided diagnosis: A comprehensive tissue structure segmentation method.
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Tey WK, Kuang YC, Ooi MP, and Khoo JJ
- Subjects
- Algorithms, Automation, Biopsy, Fibrosis, Humans, Kidney Diseases pathology, Sensitivity and Specificity, Diagnosis, Computer-Assisted methods, Kidney Diseases diagnostic imaging
- Abstract
Interstitial fibrosis in renal biopsy samples is a scarring tissue structure that may be visually quantified by pathologists as an indicator to the presence and extent of chronic kidney disease. The standard method of quantification by visual evaluation presents reproducibility issues in the diagnoses. This study proposes an automated quantification system for measuring the amount of interstitial fibrosis in renal biopsy images as a consistent basis of comparison among pathologists. The system extracts and segments the renal tissue structures based on colour information and structural assumptions of the tissue structures. The regions in the biopsy representing the interstitial fibrosis are deduced through the elimination of non-interstitial fibrosis structures from the biopsy area and quantified as a percentage of the total area of the biopsy sample. A ground truth image dataset has been manually prepared by consulting an experienced pathologist for the validation of the segmentation algorithms. The results from experiments involving experienced pathologists have demonstrated a good correlation in quantification result between the automated system and the pathologists' visual evaluation. Experiments investigating the variability in pathologists also proved the automated quantification error rate to be on par with the average intra-observer variability in pathologists' quantification., Background and Objective: Interstitial fibrosis in renal biopsy samples is a scarring tissue structure that may be visually quantified by pathologists as an indicator to the presence and extent of chronic kidney disease. The standard method of quantification by visual evaluation presents reproducibility issues in the diagnoses due to the uncertainties in human judgement., Methods: An automated quantification system for accurately measuring the amount of interstitial fibrosis in renal biopsy images is presented as a consistent basis of comparison among pathologists. The system identifies the renal tissue structures through knowledge-based rules employing colour space transformations and structural features extraction from the images. In particular, the renal glomerulus identification is based on a multiscale textural feature analysis and a support vector machine. The regions in the biopsy representing interstitial fibrosis are deduced through the elimination of non-interstitial fibrosis structures from the biopsy area. The experiments conducted evaluate the system in terms of quantification accuracy, intra- and inter-observer variability in visual quantification by pathologists, and the effect introduced by the automated quantification system on the pathologists' diagnosis., Results: A 40-image ground truth dataset has been manually prepared by consulting an experienced pathologist for the validation of the segmentation algorithms. The results from experiments involving experienced pathologists have demonstrated an average error of 9 percentage points in quantification result between the automated system and the pathologists' visual evaluation. Experiments investigating the variability in pathologists involving samples from 70 kidney patients also proved the automated quantification error rate to be on par with the average intra-observer variability in pathologists' quantification., Conclusions: The accuracy of the proposed quantification system has been validated with the ground truth dataset and compared against the pathologists' quantification results. It has been shown that the correlation between different pathologists' estimation of interstitial fibrosis area has significantly improved, demonstrating the effectiveness of the quantification system as a diagnostic aide., (Copyright © 2017 Elsevier B.V. All rights reserved.)
- Published
- 2018
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37. Oral immunization of a non-recombinant Lactococcus lactis surface displaying influenza hemagglutinin 1 (HA1) induces mucosal immunity in mice.
- Author
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Jee PF, Tiong V, Shu MH, Khoo JJ, Wong WF, Abdul Rahim R, AbuBakar S, and Chang LY
- Subjects
- Administration, Oral, Animals, Enzyme-Linked Immunosorbent Assay, Female, Humans, Influenza Vaccines immunology, Mice, Mice, Inbred BALB C, Hemagglutinin Glycoproteins, Influenza Virus immunology, Immunity, Mucosal, Influenza Vaccines administration & dosage, Lactococcus lactis metabolism
- Abstract
Mucosal immunization of influenza vaccine is potentially an effective approach for the prevention and control of influenza. The objective of the present study was to evaluate the ability of oral immunization with a non-recombinant Lactococcus lactis displaying HA1/L/AcmA recombinant protein, LL-HA1/L/AcmA, to induce mucosal immune responses and to accord protection against influenza virus infection in mice. The LL-HA1/L/AcmA was orally administered into mice and the immune response was evaluated. Mice immunized with LL-HA1/L/AcmA developed detectable specific sIgA in faecal extract, small intestine wash, BAL fluid and nasal fluid. The results obtained demonstrated that oral immunization of mice with LL-HA1/L/AcmA elicited mucosal immunity in both the gastrointestinal tract and the respiratory tract. The protective efficacy of LL-HA1/L/AcmA in immunized mice against a lethal dose challenge with influenza virus was also assessed. Upon challenge, the non-immunized group of mice showed high susceptibility to influenza virus infection. In contrast, 7/8 of mice orally immunized with LL-HA1/L/AcmA survived. In conclusion, oral administration of LL-HA1/L/AcmA in mice induced mucosal immunity and most importantly, provided protection against lethal influenza virus challenge. These results highlight the potential application of L. lactis as a platform for delivery of influenza virus vaccine.
- Published
- 2017
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38. Detection in Malaysia of a Borrelia sp. From Haemaphysalis hystricis (Ixodida: Ixodidae).
- Author
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Khoo JJ, Lim FS, Tan KK, Chen FS, Phoon WH, Khor CS, Pike BL, Chang LY, and AbuBakar S
- Subjects
- Animals, Borrelia genetics, Flagellin genetics, Malaysia, Phylogeny, RNA, Bacterial genetics, RNA, Ribosomal, 16S genetics, Sequence Analysis, RNA, Sus scrofa parasitology, Borrelia classification, Borrelia isolation & purification, Ixodidae microbiology
- Abstract
Spirochetes from the Borrelia genus are known to cause diseases in humans, namely Lyme disease and relapsing fever. These organisms are commonly transmitted to humans by arthropod vectors including ticks, mite, and lice. Here, we report the molecular detection of a Borrelia sp. from a Haemaphysalis hystricis Supino tick collected from wildlife in an Orang Asli settlement in Selangor, Malaysia. Phylogenetic analyses of partial 16s rRNA and flaB gene sequences revealed that the Borrelia sp. is closely related to the relapsing fever group borreliae, Borrelia lonestari, Borrelia miyamotoi, and Borrelia theileri, as well as a number of uncharacterized Borrelia sp. from ticks in Portugal and Japan. To our knowledge, this is the first report of a Borrelia sp. detected in H. hystricis, and in Malaysia. The zoonotic potential of this Borrelia sp. merits further investigation., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2017
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39. Coxiella Detection in Ticks from Wildlife and Livestock in Malaysia.
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Khoo JJ, Lim FS, Chen F, Phoon WH, Khor CS, Pike BL, Chang LY, and AbuBakar S
- Subjects
- Animals, Bacterial Proteins genetics, DNA, Bacterial genetics, Female, Goat Diseases epidemiology, Goat Diseases parasitology, Goats, Malaysia epidemiology, Male, Phylogeny, RNA, Bacterial genetics, RNA, Ribosomal, 16S genetics, Tick Infestations epidemiology, Animals, Wild parasitology, Coxiella isolation & purification, Livestock parasitology, Tick Infestations veterinary, Ticks microbiology
- Abstract
Recent studies have shown that ticks harbor Coxiella-like bacteria, which are potentially tick-specific endosymbionts. We recently described the detection of Coxiella-like bacteria and possibly Coxiella burnetii in ticks found from rural areas in Malaysia. In the present study, we collected ticks, including Haemaphysalis bispinosa, Haemaphysalis hystricis, Dermacentor compactus, Dermacentor steini, and Amblyomma sp. from wildlife and domesticated goats from four different locations in Malaysia. Coxiella 16s rRNA genomic sequences were detected by PCR in 89% of ticks tested. Similarity analysis and phylogenetic analyses of the 16s rRNA and rpoB partial sequences were performed for 10 representative samples selected based on the tick species, sex, and location. The findings here suggested the presence of C. burnetii in two samples, each from D. steini and H. hystricis. The sequences of both samples clustered with published C. burnetii sequences. The remaining eight tick samples were shown to harbor 16s rRNA sequences of Coxiella-like bacteria, which clustered phylogenetically according to the respective tick host species. The findings presented here added to the growing evidence of the association between Coxiella-like bacteria and ticks across species and geographical boundaries. The importance of C. burnetii found in ticks in Malaysia warrants further investigation., Competing Interests: Author Disclosure Statement The authors declare that they have no competing interests. B.L.P. is a military service member of the U.S. Government. This work was prepared as part of his official duties. The opinions and assertions contained herein are those of the author(s) and are not to be construed as official or reflecting the views of the Department of the Navy, Department of Defense, or the U.S. Government. Title 17 U.S.C. §105 provides that “Copyright protection under this title is not available for any work of the United States Government.” Title 17 U.S.C. §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person's official duties.
- Published
- 2016
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40. Adrenal vein sampling versus CT scanning in primary aldosteronism.
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Puar TH, Khoo JJ, Ng KS, Kam JW, and Wang KW
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- Adrenal Glands, Aldosterone, Humans, Hyperaldosteronism, Tomography, X-Ray Computed
- Published
- 2016
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41. Skill validation study on sentinel lymph node biopsy in breast cancer and the challenges of false-negative, in-transit and micrometastatic nodes.
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Ng CS, Arulanantham S, Khoo JJ, Sabaratnam S, Lee YF, and Ngim CF
- Subjects
- Axilla, Clinical Competence, False Negative Reactions, Female, Humans, Lymph Nodes, Lymphatic Metastasis, Breast Neoplasms diagnosis, Sentinel Lymph Node Biopsy
- Abstract
No abstract available.
- Published
- 2016
42. Bacterial community in Haemaphysalis ticks of domesticated animals from the Orang Asli communities in Malaysia.
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Khoo JJ, Chen F, Kho KL, Ahmad Shanizza AI, Lim FS, Tan KK, Chang LY, and AbuBakar S
- Subjects
- Anaplasma genetics, Anaplasma isolation & purification, Animals, Bacillus genetics, Bacillus isolation & purification, Cats parasitology, Chickens parasitology, Coxiella genetics, Coxiella isolation & purification, DNA, Bacterial genetics, Dogs parasitology, Ehrlichia genetics, Ehrlichia isolation & purification, Malaysia epidemiology, Mycobacterium genetics, Mycobacterium isolation & purification, Phylogeny, Polymerase Chain Reaction, Pseudomonas genetics, Pseudomonas isolation & purification, RNA, Ribosomal, 16S genetics, Rickettsia genetics, Rickettsia isolation & purification, Sphingomonas genetics, Sphingomonas isolation & purification, Tick Infestations epidemiology, Animals, Domestic, Bacteria isolation & purification, Ixodidae microbiology, Microbiota, Tick Infestations veterinary
- Abstract
Ticks are vectors in the transmission of many important infectious diseases in human and animals. Ticks can be readily found in the semi-forested areas such as the settlements of the indigenous people in Malaysia, the Orang Asli. There is still minimal information available on the bacterial agents associated with ticks found in Malaysia. We performed a survey of the bacterial communities associated with ticks collected from domestic animals found in two Orang Asli villages in Malaysia. We collected 62 ticks, microscopically and molecularly identified as related to Haemaphysalis wellingtoni, Haemaphysalis hystricis and Haemaphysalis bispinosa. Bacterial 16s rRNA hypervariable region (V6) amplicon libraries prepared from the tick samples were sequenced on the Ion Torrent PGM platform. We detected a total of 392 possible bacterial genera after pooling and sequencing 20 samples, indicating a diverse bacterial community profile. Dominant taxa include the potential tick endosymbiont, Coxiella. Other dominant taxa include the tick-associated pathogen, Rickettsia, and environmental bacteria such as Bacillus, Mycobacterium, Sphingomonas and Pseudomonas. Other known tick-associated bacteria were also detected, including Anaplasma, Ehrlichia, Rickettsiella and Wolbachia, albeit at very low abundance. Specific PCR was performed on selected samples to identify Rickettsia and Coxiella. Sequence of Rickettsia felis, which causes spotted fever in human and cats, was identified in one sample. Coxiella endosymbionts were detected in three samples. This study provides the baseline knowledge of the microbiome of ticks in Malaysia, focusing on tick-associated bacteria affecting the Orang Asli communities. The role of the herein found Coxiella and Rickettsia in tick physiology or disease transmission merits further investigation., (Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.)
- Published
- 2016
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43. Sentinel Node Biopsy Examination for Breast Cancer in a Routine Laboratory Practice: Results of a Pilot Study.
- Author
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Khoo JJ, Ng CS, Sabaratnam S, and Arulanantham S
- Subjects
- Adult, Aged, Aged, 80 and over, Axilla, Breast Neoplasms surgery, Carcinoma, Ductal, Breast surgery, Carcinoma, Lobular surgery, Female, Follow-Up Studies, Humans, Lymph Nodes surgery, Lymphatic Metastasis, Middle Aged, Neoplasm Invasiveness, Neoplasm Micrometastasis, Neoplasm Staging, Pilot Projects, Prognosis, Prospective Studies, Sentinel Lymph Node Biopsy, Breast Neoplasms pathology, Carcinoma, Ductal, Breast secondary, Carcinoma, Lobular secondary, Lymph Nodes pathology
- Abstract
Background: Examination of sentinel lymph node (SLN) biopsies provides accurate nodal staging for breast cancer and plays a key role in patient management. Procurement of SLNs and the methods used to process specimens are equally important. Increasing the level of detail in histopathological examination of SLNs increases detection of metastatic tumours but will also increase the burden of busy laboratories and thus may not be carried out routinely. Recommendation of a reasonable standard in SLN examination is required to ensure high sensitivity of results while maintaining a manageable practice workload., Materials and Methods: Twenty-four patients with clinically node-negative breast cancer were recruited. Combined radiotracer and blue dye methods were used for identification of SLNs. The nodes were thinly sliced and embedded. Serial sectioning and immunohistochemical (IHC) staining against AE1/AE3 were performed if initial HandE sections of the blocks were negative., Results: SLNs were successfully identified in all patients. Ten cases had nodal metastases with 7 detected in SLNs and 3 detected only in axillary nodes (false negative rate, FNR=30%). Some 5 out of 7 metastatic lesions in the SLNs (71.4%) were detected in initial sections of the thinly sliced tissue. Serial sectioning detected the remaining two cases with either micrometastases or isolated tumour cells (ITC)., Conclusions: Thin slicing of tissue to 3-5mm thickness and serial sectioning improved the detection of micro and macro-metastases but the additional burden of serial sectioning gave low yield of micrometastases or ITC and may not be cost effective. IHC validation did not further increase sensitivity of detection. Therefore its use should only be limited to confirmation of suspicious lesions. False negative cases where SLNs were not involved could be due to skipped metastases to non-sentinel nodes or poor technique during procurement, resulting in missed detection of actual SLNs.
- Published
- 2016
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44. Independent Emergence of the Cosmopolitan Asian Chikungunya Virus, Philippines 2012.
- Author
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Tan KK, Sy AK, Tandoc AO, Khoo JJ, Sulaiman S, Chang LY, and AbuBakar S
- Subjects
- Chikungunya virus classification, Chikungunya virus isolation & purification, Disease Outbreaks statistics & numerical data, Female, Humans, Male, Mutation genetics, Philippines epidemiology, Chikungunya Fever epidemiology, Chikungunya Fever virology, Chikungunya virus genetics, Communicable Diseases, Emerging epidemiology, Communicable Diseases, Emerging virology, Genome, Viral genetics
- Abstract
Outbreaks involving the Asian genotype Chikungunya virus (CHIKV) caused over one million infections in the Americas recently. The outbreak was preceded by a major nationwide outbreak in the Philippines. We examined the phylogenetic and phylogeographic relationships of representative CHIKV isolates obtained from the 2012 Philippines outbreak with other CHIKV isolates collected globally. Asian CHIKV isolated from the Philippines, China, Micronesia and Caribbean regions were found closely related, herein denoted as Cosmopolitan Asian CHIKV (CACV). Three adaptive amino acid substitutions in nsP3 (D483N), E1 (P397L) and E3 (Q19R) were identified among CACV. Acquisition of the nsP3-483N mutation in Compostela Valley followed by E1-397L/E3-19R in Laguna preceded the nationwide spread in the Philippines. The China isolates possessed two of the amino acid substitutions, nsP3-D483N and E1-P397L whereas the Micronesian and Caribbean CHIKV inherited all the three amino acid substitutions. The unique amino acid substitutions observed among the isolates suggest multiple independent virus dissemination events. The possible biological importance of the specific genetic signatures associated with the rapid global of the virus is not known and warrant future in-depth study and epidemiological follow-up. Molecular evidence, however, supports the Philippines outbreak as the possible origin of the CACV.
- Published
- 2015
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45. Pediatric appendicitis in a developing country: what are the clinical predictors and outcome of perforation?
- Author
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Ngim CF, Quek KF, Dhanoa A, Khoo JJ, Vellusamy M, and Ng CS
- Subjects
- Abdominal Abscess epidemiology, Adolescent, Appendicitis complications, Appendicitis epidemiology, Child, Child, Preschool, Cross-Sectional Studies, Female, Humans, Infant, Intestinal Perforation etiology, Length of Stay, Leukocyte Count, Logistic Models, Male, Postoperative Period, Predictive Value of Tests, Retrospective Studies, Risk Factors, Treatment Outcome, Abdominal Abscess etiology, Appendectomy, Appendicitis surgery, Intestinal Perforation diagnosis
- Abstract
Objectives: This study explored the risk factors and outcomes associated with perforation in children who underwent emergency appendicectomies., Methods: A retrospective cross-sectional study was conducted on children <13 years old who underwent appendicectomies in a Malaysian hospital in 2007., Results: One hundred thirty-four children underwent appendicectomies of which 118 were confirmed histologically. Sixty-one (52%) were perforated. Children with perforation had significantly longer duration of symptoms (p < 0.001), higher white cell count and absolute neutrophil counts (p = 0.013), with longer intra-operative period (p < 0.001) and post-operative recovery period (p < 0.001). Of the 52 samples of pus collected intra-operatively, 37 (71.1%) yielded positive cultures that were predominantly Escherichia coli (n = 27). Both the patients who had Staphylococcus aureus cultured from pus collected intra-operatively had significant pyogenic complications (scrotal pyocele and intra-abdominal abscess)., Conclusion: Children whose appendicitis were perforated had longer duration of symptoms, higher white cell counts and absolute neutrophil counts. Those with S.aureus cultured from intra-operative pus appeared to suffer more complications., (© The Author [2014]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2014
- Full Text
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46. Pattern of hMLH1, hMSH2 and hMSH6 expression and clinical characteristics in a sample of Malaysian colorectal carcinoma cases.
- Author
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Khoo JJ, Gunn A, and Peh SC
- Subjects
- Adaptor Proteins, Signal Transducing analysis, Carcinoma mortality, Carcinoma pathology, Colorectal Neoplasms mortality, Colorectal Neoplasms pathology, DNA-Binding Proteins analysis, Female, Humans, Immunohistochemistry, Kaplan-Meier Estimate, Malaysia, Male, Middle Aged, MutL Protein Homolog 1, MutS Homolog 2 Protein analysis, Nuclear Proteins analysis, Adaptor Proteins, Signal Transducing biosynthesis, Biomarkers, Tumor analysis, Carcinoma metabolism, Colorectal Neoplasms metabolism, DNA-Binding Proteins biosynthesis, MutS Homolog 2 Protein biosynthesis, Nuclear Proteins biosynthesis
- Abstract
Malignant transformation from normal colonic mucosa to carcinomas may be accelerated by genetic loss or inactivation of genes of the DNA mismatch repair system. The aim of the study was to determine the local incidence and pattern of immunohistochemical expression of mismatch repair proteins namely: hMLH1, hMSH2 and hMSH6 in a series of colorectal carcinomas (CRCs) and correlate this to their clinical and pathological features. Forty-three out of 298 cases of CRCs (14.4%) showed abnormal staining pattern for mismatch repair proteins with a majority (65.1%) showing single hMLH1 loss. Tumours with mismatch repair defect (MMR-d) were frequently found at the right side of colon (p<0.001), poorly differentiated carcinomas (p<0.001), produced more mucin (p=0.007), exophytic growth (p=0.007) and were bigger (p=0.002) than tumours with no mismatch repair defect. Immunohistochemical stains for mismatch repair proteins could be done in local laboratories on these selected cases before referring for the expensive molecular test.
- Published
- 2013
47. Mitochondrially localised MUL1 is a novel modulator of antiviral signaling.
- Author
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Jenkins K, Khoo JJ, Sadler A, Piganis R, Wang D, Borg NA, Hjerrild K, Gould J, Thomas BJ, Nagley P, Hertzog PJ, and Mansell A
- Subjects
- Adaptor Proteins, Signal Transducing metabolism, Chemokine CCL5 metabolism, Cytokines metabolism, DEAD Box Protein 58, DEAD-box RNA Helicases metabolism, HEK293 Cells, Humans, Inflammation pathology, Polyubiquitin metabolism, Protein Binding, Protein Processing, Post-Translational, Protein Transport, Receptors, Immunologic, SUMO-1 Protein metabolism, Ubiquitination, Antiviral Agents metabolism, Mitochondria metabolism, Signal Transduction immunology, Ubiquitin-Protein Ligases metabolism
- Abstract
The innate immune response to virus must be balanced to eliminate infection yet limit damaging inflammation. A critical arm of the antiviral response is launched by the retinoic acid-inducible-gene I (RIG-I) protein. RIG-I is activated by viral RNA then associates with the mitochondrial antiviral signaling (MAVS) protein to subsequently induce potent inflammatory cytokines. Here, we demonstrate the mitochondrial E3 ubiquitin protein ligase 1 (MUL1) is a crucial moderator of RIG-I signaling. MUL1 is localized to the mitochondria where it interacts with MAVS and catalyzes RIG-I post-translational modifications that inhibit RIG-I-dependent cell signaling. Accordingly, depletion of MUL1 potentiated RIG-I mediated nuclear factor-kappa B (NF-κB) and interferon (IFN) β reporter activity. Moreover, depletion of MUL1 boosted the antiviral response and increased proinflammatory cytokines following challenge with the RNA mimetic poly I:C and Sendai virus. We therefore submit that MUL1 is a novel regulator of the RIG-I-like receptor-dependent antiviral response, that otherwise functions to limit inflammation.
- Published
- 2013
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48. Association between glycemic control and hip fracture.
- Author
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Puar TH, Khoo JJ, Cho LW, Xu Y, Chen YT, Chuo AM, Poh CB, and Ng JM
- Subjects
- Aged, Case-Control Studies, Diabetes Mellitus, Type 2 complications, Diabetes Mellitus, Type 2 drug therapy, Female, Hip Fractures etiology, Humans, Male, Retrospective Studies, Risk Factors, Blood Glucose analysis, Diabetes Mellitus, Type 2 blood, Glycated Hemoglobin analysis, Hip Fractures epidemiology
- Abstract
Objectives: To determine whether tight glycemic control is associated with greater risk of hip fractures in individuals being treated for type 2 diabetes mellitus., Design: Case-control study., Setting: Tertiary hospital., Participants: Cases were selected from all individuals with diabetes mellitus admitted between 2005 and 2010 to Changi General Hospital for hip fracture (N = 932). Cases were included if their glycosylated hemoglobin (HbA1c) had been measured within 3 months of the fracture and they were undergoing treatment with oral hypoglycemic medications or insulin. Each case was matched with one control for sex, age, race, duration of diabetes mellitus, and comorbidities., Measurements: Information on baseline characteristics, HbA1c, and use of diabetic medications was obtained. The likelihood of hip fracture was determined comparing four different values of HbA1c [<6%, 6.1-7.0%, 7.1-8.0%, >8% (reference group)] and use of diabetic medications., Results: The mean age of cases was 77.3 ± 7.7, and 73.3% were female. After adjusting for age, sex, race, comorbidities, and other covariates, participants with tighter glycemic control (HbA1c < 6% and 6.1-7.0%) were more likely to have a hip fracture than those with HbA1c >8% (odds ratio (OR) = 3.01, 95% confidence interval (CI) = 2.01-4.51, P < .001; and OR = 2.34, 95% CI=1.71-3.22, P < .001, respectively). The use of insulin and sulfonylurea was similar between cases and controls., Conclusion: The present study found an association between tight glycemic control (when HbA1c < 7%) and greater risk of hip fracture in individuals being treated for type 2 diabetes mellitus. Greater caution needs to be exercised in treating older patients with diabetes mellitus., (© 2012, Copyright the Authors Journal compilation © 2012, The American Geriatrics Society.)
- Published
- 2012
- Full Text
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49. Phaeochromocytoma mimicking scleroderma.
- Author
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Khoo JJ and Pratt EJ
- Abstract
We describe a patient with adrenal phaeochromocytoma who presented with peripheral vasospasm and ischaemia and other manifestations mimicking features of systemic sclerosis, which resolved after resection of the tumor. Phaeochromocytoma should be suspected in patients with features of scleroderma who are negative for auto-antibodies.
- Published
- 2011
- Full Text
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50. Toll-like receptors as interferon-regulated genes and their role in disease.
- Author
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Khoo JJ, Forster S, and Mansell A
- Subjects
- Animals, Humans, Protein Isoforms genetics, Protein Isoforms metabolism, Signal Transduction, Toll-Like Receptors genetics, Gene Expression Regulation, Immunity, Innate, Interferons metabolism, Toll-Like Receptors metabolism
- Abstract
The Toll-like receptors (TLRs) are innate sensors that recognize both microbial and endogenous ligands, initiating the host defense response. TLRs initiate the potent proinflammatory response to infection, are the target for adjuvants, and are essential for the establishment and maturation of adaptive immunity. As such they have been the interest of widespread research and the target of therapeutic intervention on multiple diseases. It has become apparent that expression of a subset of TLRs (TLR1, TLR2, TLR3, TLR5, and TLR7) is induced by Type I interferons (IFN). The role and impact of IFN expression on TLR responses is therefore critical in understanding the role of TLRs in disease, particularly as IFN itself is a downstream gene induced by specific TLRs. In this review we discuss the function and role of IFN-regulated TLRs in disease and how the role of IFN may impact upon TLR induction of the immune response in diseases, particularly in mouse models.
- Published
- 2011
- Full Text
- View/download PDF
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