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Purpose: Despite readily available over-the-counter drugs, most herbal products are not scientifically validated for their safety profile. The study aimed to evaluate the safety profile of marketed anti-diabetic herbal medicines in Ghana. Design/Methodology/Approach: Four antidiabetic herbal medicines were purchased from herbal shops at Okaishie market in Accra. The mixtures were dried at 70oC in a water bath to obtain powdered extracts. A single dose of 5000mg/kg body weight of each extract was administered to 10 female Sprague Dawley rats once for the acute toxicity studies, and signs of toxicity were observed. Histopathological examination of essential organs was conducted after sacrificing the rats. P < 0.05 was considered statistically significant after multiple comparison tests. Findings: No mortality or adverse side effects were recorded. The rats' normal growth, food, and water consumption were observed during the study period. No significant biochemical or haematological differences were observed, and no significant histological alterations were observed in the tissues studied. Research Limitation: This study used a specific batch of screened antidiabetic herbal medicines, and the results cannot be generalised to all batches of these herbal medicines. Practical Implication: It will help the Food and Drugs Authority, Ghana Standard Authority, Ministry of Health, and Ghana Health Service to intensify their surveillance of these antidiabetic herbal medicines. Social Implication: Safety evaluation of herbal medicines is vital in protecting society from serious adverse health effects from harmful herbal products. Originality/Value: The study employs laboratory animals to assess these herbal medicines for safety evaluations. Rats have almost the same physiology and anatomy as humans. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has highlighted the critical need for accurate and efficient diagnostic tools for detecting severe acute respiratory coronavirus 2 (SARS-CoV-2) infections. This study presents a comparison of two diagnostic tests: RT-PCR and antigen detection rapid diagnostic tests (Ag-RDTs). This study focused on their performance, variant specificity, and their clinical implications. A simultaneous testing of 268 samples was carried out for SARS-CoV-2 using RT-PCR and Ag-RDTs [flourescence immunoassay (FIA) and lateral flow immunoassay (LFIA)]. Viral load was quantified, and variant identification was performed using a PCR-based assay. The prevalence was found to be 30.2% using reverse transcription PCR (RT-PCR), 26.5% using FIA, and 25% using LFIA. When comparing the FIA and LFIA, the overall diagnostic performance was found to be 80.25% vs 76.54%, 96.79% vs 97.33%, 91.55% vs 90.51%, and 91.88% vs 92.56% for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), respectively. Both Ag-RDTs showed a strong agreement with RT-PCR (κ = 0.78-0.80). The overall accuracies of the FIA and LFIA were 92.41% and 92.13%, respectively. The FIA showed higher sensitivity (73.68%) and PPV (92.08%) than the LFIA (65.79% and 90.56%, respectively) in asymptomatic patients. At low Ct values (<25), both Ag-RDTs had 100% sensitivity, but the sensitivity reduced to 31.82% for FIA and 27.27% for LFIA at Ct values > 30. The diagnostic sensitivity of FIA compared to LFIA for detecting the Alpha variant was 78.85% vs. 69.23% and 72.22% vs. 83.33% for the Delta variant. Both Ag-RDTs had 100% sensitivity for detecting Omicron. Both Ag-RDTs performed well in patients with high viral loads and Omicron variant infections compared to those infected with Alpha and Delta variants. This study confirms the comparable performance of RT-PCR and Ag-RDTs, specifically FIA and LFIA, for SARS-CoV-2 detection. The FIA showed higher sensitivity and PPV in asymptomatic cases, while both Ag-RDTs exhibited strong agreement with RT-PCR results. Notably, Ag-RDTs, particularly FIA, proved effective in detecting the Omicron variant and cases with high viral loads, highlighting their potential clinical utility in managing the COVID-19 pandemic.IMPORTANCEThis study is of utmost importance in providing effective responses to manage the COVID-19 pandemic. It rigorously compares the diagnostic accuracy, variant specificity, and practical considerations of reverse transcription PCR (RT-PCR) and antigen detection rapid diagnostic tests (Ag-RDTs) for severe acute respiratory coronavirus 2 (SARS-CoV-2), answering critical questions. The results of this study will help healthcare professionals choose the appropriate testing methods, allocate resources effectively, and enhance public health strategies. Given the evolution of the virus, understanding the performance of these diagnostic tools is crucial to adapting to emerging variants. Additionally, the study provides insights into logistical challenges and accessibility issues, which will contribute to refining testing workflows, particularly in resource-limited settings. Ultimately, the study's impact extends to global healthcare, providing valuable information for policymakers, clinicians, and public health officials as they work together for mitigating the impact of the pandemic., Competing Interests: The authors declare no conflict of interest.

Introduction: Currently, sequencing has been the only tool for the identification of circulating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants. However, it is known to be an expensive and laborious approach involving high technical expertise. Considering the reduced adherence to preventive measures postlockdown in Accra, this study presents an alternative method that leverages polymerase chain reaction (PCR) to identify circulating SARS-CoV-2 variants in the Accra Metropolis postlockdown., Methods: This prospective cross-sectional study was conducted between July and December 2022. Nasopharyngeal samples were collected from 268 consenting participants. Samples were subjected to nucleic acid extraction and followed by real-time polymerase chain reaction for the detection and quantification of SARS-CoV-2 RNA. SARS-CoV-2 positive samples were subsequently subjected to variant identification using rapid PCR. Findings . The prevalence of SARS-CoV-2 within the Accra Metropolis was 30.2%. The majority of the SARS-CoV-2 infection was diagnosed in females, participants aged 41-50 years, and symptomatic participants. Participants aged ≤10 years and females recorded the highest viral load while participants aged 41-50 years recorded the highest number of infections. The SARS-CoV-2 variants detected were Alpha (64.2%), Delta (22.2%), and Omicron (13.6%). Predictors of SARS-CoV-2 infection identified were chills, cough, headache, body weakness, sore throat, and dyspnoea in order of decreasing association with SARS-CoV-2 infection. There was a strong association between symptom status, gender, age, and SARS-CoV-2 infection., Conclusion: There was a high prevalence of SARS-CoV-2 within the Accra Metropolis postlockdown within the sampling period. The Alpha variant of SARS-CoV-2 is the predominant circulating variant, and persons presenting with symptoms are most likely to be diagnosed with COVID-19. Children aged ≤10 years serve as a reservoir for infection transmission., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2024 Frank T. Aboagye et al.)

Background: Progress toward malaria elimination is increasing as many countries near zero indigenous malaria cases. In settings nearing elimination, interventions will be most effective at interrupting transmission when targeted at the residual foci of transmission. These foci may be missed due to asymptomatic infections. To solve this problem, the World Health Organization recommends reactive case detection (RACD). This case study was conducted to identify individuals with asymptomatic malaria, their predisposing risk factors and recommend RACD in Asutsuare, Ghana based on literature review and a cross sectional study., Methods: The study involved a search on PubMed and Google Scholar of literature published between 1st January, 2009-14th August, 2023 using the search terms "malaria" in "Asutsuare". Furthermore, structured questionnaires were administered to one hundred individuals without symptoms of malaria and screened using rapid diagnostic test (RDT) kits, microscopy and real-time polymerase chain reaction (rt-PCR). Malaria prevalence based on the three diagnostic techniques as well as potential malaria risk factors were assessed through questionnaires in a cross-sectional study., Results: Cumulatively, sixty-four (64) studies (Google Scholar, 57 and PubMed, 7) were reviewed and 22 studies included in the literature on malaria in Asutsuare, Ghana. Significant risk factors were occupation, distance from a house to a waterbody, age group and educational level. Out of the 100 samples, 3 (3%) were positive by RDT, 6 (6%) by microscopy and 9 (9%) by rt-PCR. Ages 5-14.9 years had the highest mean malaria parasite densities of 560 parasites/µl with Plasmodium falciparum as the dominant species in 4 participants. Moreover, in the age group ≥ 15, 2 participants (1 each) harboured P. falciparum and Plasmodium malariae parasites. RDT had a higher sensitivity (76.54%; CI 95 66.82-85.54) than rt-PCR (33.33%; CI 95 4.33-77.72), while both rt-PCR and RDT were observed to have a higher specificity (92.55; CI 95 85.26-96.95) and (97.30; CI 95 93.87-99.13), respectively in the diagnosis of malaria., Conclusion: In Asutsuare, Ghana, a low endemic area, the elimination of malaria may require finding individuals with asymptomatic infections. Given the low prevalence of asymptomatic individuals identified in this study and as repleted in the literature review, which favours RACD, Asutsuare is a possible setting receptive for RACD implementation., (© 2024. The Author(s).)

Background: In Ghana, Cymbopogon citratus leaves together with guava, pawpaw, and lime are processed into a decoction to treat fever. To encourage its usage, preclinical validation of the safety profile of the plant is required. The acute and subchronic toxicities of the conventional Soxhlet ethanolic Cymbopogon citratus leaves extract in Sprague-Dawley rats were investigated., Methods: Pulverized Cymbopogon citratus leaves were extracted with 98% ethanol using the conventional Soxhlet extraction (CSE) method and dried. In the acute toxicity study, a single dose of 5000 mg/kg body weight was administered to six female Sprague-Dawley rats and 1 ml/100 g body weight normal saline to control (6) once, and signs of toxicity were observed every hour for the first 12 hr, 24 hr, and 48 hr through to 14 days. In the subchronic study, the treatment groups were administered 200 mg/kg, 600 mg/kg, and 1200 mg/kg, respectively, of the CSE C. citratus leaves extract for six weeks. Analyses were conducted on the blood, urine, and serum samples of the rats. Histopathological examination of the liver, heart, kidney, spleen, and lungs was carried out at termination. Analysis of variance (ANOVA) was performed to determine statistically significant differences between the test and control rats at P   <  0.05., Results: The results revealed that there were no statistically significant differences ( p   >  0.05) in the urinalysis and haematological analysis between control and test rats over the treatment period. Similarly, CSE C. citratus leaves extract did not induce any significant biochemical changes in the treatment group; however, there was a weight loss effect on the treated rats. There were no noticeable morphological changes in the heart, liver, spleen, lung, and kidney of the test rats compared to the control., Conclusion: CSE ethanolic C. citratus leaves extract has a weight loss effect, and long-term administration of the extract may not cause any organ-specific toxicity to the consumers., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Jacob Apibilla Ayembilla et al.)

Reactive case detection (RACD) is the screening of household members and neighbors of index cases reported in passive surveillance. This strategy seeks asymptomatic infections and provides treatment to break transmission without testing or treating the entire population. This review discusses and highlights RACD as a recommended strategy for the detection and elimination of asymptomatic malaria as it pertains in different countries. Relevant studies published between January 2010 and September 2022 were identified mainly through PubMed and Google Scholar. Search terms included "malaria and reactive case detection", "contact tracing", "focal screening", "case investigation", "focal screen and treat". MedCalc Software was used for data analysis, and the findings from the pooled studies were analyzed using a fixed-effect model. Summary outcomes were then presented using forest plots and tables. Fifty-four (54) studies were systematically reviewed. Of these studies, 7 met the eligibility criteria based on risk of malaria infection in individuals living with an index case < 5 years old, 13 met the eligibility criteria based on risk of malaria infection in an index case household member compared with a neighbor of an index case, and 29 met the eligibility criteria based on risk of malaria infection in individuals living with index cases, and were included in the meta-analysis. Individuals living in index case households with an average risk of 2.576 (2.540-2.612) were more at risk of malaria infection and showed pooled results of high variation heterogeneity chi-square = 235.600, ( p < 0.0001) I 2 = 98.88 [97.87-99.89]. The pooled results showed that neighbors of index cases were 0.352 [0.301-0.412] times more likely to have a malaria infection relative to index case household members, and this result was statistically significant ( p < 0.001). The identification and treatment of infectious reservoirs is critical to successful malaria elimination. Evidence to support the clustering of infections in neighborhoods, which necessitates the inclusion of neighboring households as part of the RACD strategy, was presented in this review.

Background: The rhizome of ginger (Zingiber officinale Roscoe) is one of the most patronized spices worldwide and plays an important role in folklore medicine. In this study, we aimed to determine the quality of ginger samples from representative West African (Ghana, Nigeria) and East African (Uganda, Kenya) countries. By that, we also implicitly sought to determine the probable influence of location of cultivation (and the intrinsic growth conditions) on the quality of the samples. The ginger samples were pretreated by osmosonication prior to relative humidity convective drying and analyzed for differences in their metabolomes, total phenolic content (TPC) and total flavonoid content (TFC), antioxidant activities, sensory characteristics and volatile compounds composition (via electronic-nose determination)., Results: The outcome of our study showed marked source-dependent differences in the metabolomes of the samples as captured by a metabolomics approach. Based on the findings of the metabolomics study, 6-gingerol content was quantified and found to be higher in the samples of West African origin. Also, the samples from the two West African countries contained higher levels of bioactive phytochemicals as evinced by the results of TPC, TFC, e-nose analysis, and antioxidant activities. They also gave better sensory attributes., Conclusion: In summary, for all parameters assessed, and on a country-by-country basis, the general quality trend observed was: Ghana > Nigeria > Uganda > Kenya. All results taken together, our findings at least in part, point to the influence of geographical regions of cultivation on the quality of the ginger rhizomes. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Objectives: This study sought to determine the quality of essential oil from Xylopia aethiopica fruits of different geographical origins using GC-MS-based metabolomics, bacterial quorum sensing and anti-inflammation assessment., Methods: Essential oil was obtained from eight batches of X. aethiopica fruits from Ghana and Nigeria by hydrodistillation, characterized using gas chromatography-mass spectrometry and differences therein found using metabolomics. The respective antibacterial activity of the oils was tested against four bacterial strains: two Gram-positive strains, Staphylococcus aureus (ATCC 25923) and Bacillus licheniformis (ATCC12759), and two Gram-negative strains, Escherichia coli (ATCC25922) and Klebsiella pneumoniae (ATCC 13883). Anti-inflammation was tested using RAW 264.7 macrophage cells., Key Findings: The outcome of the study revealed that the oil of the Ghana-sourced samples exhibited superior antibacterial, cytotoxic and anti-inflammatory effects than those from Nigeria. This could be attributed to the higher levels of the bioactive compounds present in those samples. This distinction between the samples from the two countries was clearly established using the metabolomics approach, and 14 differential metabolites were found to be potential chemical markers., Conclusions: The study lends credence to the traditional uses of the essential oil of X. aethiopica as an antimicrobial and anti-inflammatory agent., (© 2019 Royal Pharmaceutical Society.)

SurA, a periplasmic chaperone, is a key factor in the biogenesis of β-barrel outer membrane proteins (OMPs). It is also associated with virulence, invasion and biofilm formation in Escherichia and Salmonella species. To investigate whether SurA affects bacterial motility and biofilm formation in Salmonella enterica serovar Typhi, we prepared a surA deleted mutant. Motility assay and quantitative real-time PCR (qRT-PCR) indicated that surA deletion reduced swimming motility and decreased flagellar gene expression, respectively. β-galactosidase assay and qRT-PCR further showed that surA deletion also activated the RcsCDB pathway, which we verified affected motility. We also examined the effects of the surA deletion on biofilm formation and established that the surA mutant exhibited significantly reduced ability to form biofilms compared with the wild-type. From our findings, we proposed that the periplasmic chaperone, SurA, affects flagella expression via the RcsCDB pathway thereby influencing biofilm formation in Salmonella enterica serovar Typhi. Collectively, these studies confirmed a new physiological role for SurA in Salmonella enterica serovar Typhi.

Vibrio parahaemolyticus, the leading cause of seafood-associated gastroenteritis worldwide, requires the two type-III secretion systems (T3SS1 and T3SS2) and a thermostable direct hemolysin (encoded by tdh1 and tdh2) for full virulence. The tdh genes and the T3SS2 gene cluster constitute an 80 kb pathogenicity island known as Vp-PAI located on the chromosome II. Expression of T3SS1 and Vp-PAI is regulated in a quorum sensing (QS)-dependent manner but its detailed mechanisms remain unknown. Herein, we show that three factors (QS regulators AphA and OpaR and an AraC-type transcriptional regulator QsvR) form a complex regulatory network to control the expression of T3SS1 and Vp-PAI genes. At low cell density (LCD), whereas Vp-PAI expression is repressed, T3SS1 genes are induced by AphA, which directly binds (an operator region of) the exsBAD-vscBCD operon. At high cell density (HCD), the bacterium turns off T3SS1 expression by replacing AphA with OpaR, triggering the induction of Vp-PAI. Furthermore, QsvR binds to the regulatory regions of all the tested T3SS1 and Vp-PAI genes to activate their transcription at HCD. Taken together, our data highlight how multiple QS regulators contribute to the pathogenicity of V. parahaemolyticus by precisely controlling the expression of major virulence determinants during different stages of growth., (© 2019 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Salmonella enterica serovar Typhi (S. Typhi) is a human enteropathogen that can overcome oxidative stress and survive in macrophages. OxyR is an important part of the antioxidant defense system. S. Typhi expresses a virulence (Vi) polysaccharide capsular antigen, which provides the bacterium with the ability to avoid host defenses and suppress detection by the innate immune system. This study investigated the effect of OxyR on Vi antigen in S. Typhi. In the oxyR mutant strain, microarray analysis, quantitative real time PCR and β-galactosidase assay confirmed that the viaB operon was positively regulated by OxyR. The Vi enzyme-linked immunosorbent assay and flow cytometry results showed that Vi capsule level was decreased in the oxyR mutant strain. Also, the EMSA revealed that OxyR directly binds to the promoter region of tviA. Thus, we propose that S. Typhi OxyR positively regulates expression of Vi capsule antigen in a direct manner., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Vibrio parahaemolyticus , the leading causative agent of seafood-associated gastroenteritis, harbors two major virulence gene loci T3SS1 and Vp-PAI (T3SS2 and tdh2 ). ToxR is a virulence regulator of vibrios. Cell density-dependent transcriptional pattern of toxR and its regulatory actions on T3SS1 and Vp-PAI have been previously reported, but the detailed regulatory mechanisms are still obscure. In the present work, we showed that the highest transcription level of toxR occurs at an OD 600 = 0.2-0.4, which may be due to the subtle repression of ToxR and the quorum-sensing (QS) master regulator AphA. We also showed that ToxR is involved in regulating the mouse lethality, enterotoxicity, cytotoxicity, and hemolytic activity of V. parahaemolyticus . ToxR binds to the multiple promoter-proximal DNA regions within the T3SS1 locus to repress their transcription. In addition, ToxR occupies the multiple promoter-proximal DNA regions of Vp-PAI locus to activate their transcription. Thus, ToxR regulates the multiple virulence phenotypes via directly acting on the T3SS1 and Vp-PAI genes. Data presented here provide a deeper understanding of the regulatory patterns of ToxR in V. parahaemolyticus .

Bacterial non-coding RNAs (ncRNAs) are widely studied and found to play important roles in regulating various cellular processes. Recently, many ncRNAs have been discovered to be transcribed or processed from 3' untranslated regions (3' UTRs). Here we reported a novel 3' UTR-derived ncRNA, RibS, which could influence biofilm formation of Salmonella enterica serovar Typhi (S. Typhi). RibS was confirmed to be a ∼700 nt processed product produced by RNase III-catalyzed cleavage from the 3' UTR of riboflavin synthase subunit alpha mRNA, RibE. Overexpression of RibS increased the expression of the cyclopropane fatty acid synthase gene, cfa, which was located at the antisense strand. Biofilm formation of S. Typhi was enhanced by overexpressing RibS both in the wild type strain and cfa deletion mutant. Deletion of cfa attenuated biofilm formation of S. Typhi, while complementation of cfa partly restored the phenotype. Moreover, overexpressing cfa enhanced the biofilm formation of S. Typhi. In summary, RibS has been identified as a novel ncRNA derived from the 3' UTR of RibE that promotes biofilm formation of S. Typhi, and it appears to do so, at least in part, by increasing the expression of cfa., (Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of human typhoid fever. S. Typhi expresses a major virulence determinant called Vi polysaccharide capsular antigen, which is encoded by the viaB locus containing 10 consecutive genes including tviA and tviB. Expression of Vi antigen is regulated by the two-component regulatory system EnvZ/OmpR and the global RNA-binding factor Hfq. In this study, we show that OmpR coordinates with Hfq to regulate the transcription of Vi antigen genes under osmotic stress conditions. OmpR binds to the promoters of tviA and its own genes to activate their transcription; however, it positively regulates tviB and negatively regulates hfq in an indirect manner. Moreover, Hfq reversely inhibits ompR, tviA and tviB, and positively regulates its own gene expression. Thus, we report of a complex gene regulatory network involving the reciprocal regulation and autoregulation of OmpR and Hfq, and their regulatory actions on Vi polysaccharide capsular antigen genes in S. Typhi.

Vibrio parahaemolyticus, a Gram-negative bacterium, inhabits marine and estuarine environments and it is a major pathogen responsible globally for most cases of seafood-associated gastroenteritis in humans and acute hepatopancreatic necrosis syndrome in shrimps. There has been a dramatic worldwide increase in V. parahaemolyticus infections over the last two decades. The pathogenicity of V. parahaemolyticus has been linked to the expression of different kinds of virulence factors including extracellular proteases, such as metalloproteases and serine proteases. V. parahaemolyticus expresses the metalloproteases; PrtV, VppC, VPM and the serine proteases; VPP1/Protease A, VpSP37, PrtA. Extracellular proteases have been identified as potential virulence factors which directly digest many kinds of host proteins or indirectly are involved in the processing of other toxic protein factors. This review summarizes findings on the metalloproteases and serine proteases produced by V. parahaemolyticus and their roles in infections. Identifying the role of V. parahaemolyticus virulence-associated extracellular proteases deepens our understanding of diseases caused by this bacterium.

Quorum sensing (QS), a cell-to-cell communication process, is widely distributed in the bacterial kingdom. Bacteria use QS to control gene expression in response to cell density by detecting the signal molecules called autoinducers. AphA protein is the master QS regulator of vibrios operating at low cell density. It regulates the expression of a variety of genes, especially those encoding virulence factors, flagella/motility and biofilm formation. The role and regulation of AphA in vibrios, especially in human pathogenic vibrios, are summarized in this review. Clarification of the roles of AphA will help us to understand the pathogenesis of vibrios.

Vibrio parahaemolyticus , the leading cause of seafood-associated gastroenteritis, harbors two separate T6SSs on chromosomes 1 and 2, i.e., T6SS1 (VP1386-1420) and T6SS2 (VPA1025-1046). T6SS1 contains at least 7 putative operons: VP1386-1387, VP1388-1390, VP1392-1391, VP1393-1406, VP1400-1406, VP1409-1407, and VP1410-1420. V. parahaemolyticus AphA and OpaR are the two master regulators of quorum sensing (QS) system that are highly expressed at low cell density and high cell density, respectively. ToxR is a membrane-bound virulence regulatory protein conserved across the Vibrio family. In the present work, we show that ToxR coordinates with AphA and OpaR to repress T6SS1 expression in V. parahaemolyticus . OpaR binds to the promoters of VP1388-1390, VP1400-1406, and VP1409-1407 to repress their transcription, but it appears to negatively regulate VP1393-1406 transcription in an indirect manner. By contrast, AphA negatively regulated the above four T6SS1 operons in an indirect manner. In addition, ToxR binds to the promoters of VP1400-1406 and VP1409-1407 to inhibit their transcription, but it presents an indirect interaction with VP1388-1390 and VP1393-1406 promoters. Notably, the expression of ToxR also manifested in a QS-dependent manner and the highest expression occurred at LCD. Meanwhile, the highest expression of T6SS1 occurred at an OD 600 value of 0.6 to 0.8 due to the tight regulation of ToxR and QS, suggesting T6SS1 functions only during the mid-logarithmic growth phase. These observations provide significant insight into the molecular mechanism of T6SS1 gene regulation by QS and ToxR in V. parahaemolyticus .

Vibrio parahaemolyticus expresses one major virulence determinant T6SS2, which is constituted into three putative operons, i.e., VPA1027-1024, VPA1043-1028, and VPA1044-1046. CalR, a LysR-type transcriptional regulator, was originally identified as a repressor of the swarming motility and T3SS1 gene expression. As shown in this study, CalR binds to the promoter-proximal region of each of the three operons to activate their transcription, and moreover, CalR activates the adhesion of V. parahaemolyticus to HeLa cells. In addition, competitive EMSAs demonstrated that CalR acts as an antagonist of H-NS in V. parahaemolyticus. Collectively, these studies confirmed a new physiological role for CalR in V. parahaemolyticus.

The cpsQ-mfpABC locus is transcribed as two operons, i.e., cpsQ-mfpABC and mfpABC, in Vibrio parahaemolyticus, and both of them are all required for biofilm formation. CalR belongs to the LysR-type transcriptional regulator family, and was originally identified as a repressor of the swarming motility and T3SS1 genes expression in V. parahaemolyticus. In the present work, a combination of qRT-PCR, primer extension, LacZ fusion expression, electrophoretic mobility shift assay, and DNase I footprinting assays were employed to elucidate the regulatory mechanisms of cpsQ-mfpABC and mfpABC by CalR. One transcription start site for each operon was detected and their activities were activated by CalR. His-CalR protected two DNA regions upstream of mfpABC against DNase I digestion, but no binding sites were detected in the promoter region of cpsQ-mfpABC, suggesting a direct and an indirect regulatory manner for mfpABC and cpsQ-mfpABC transcription by CalR, respectively. Collectively, the results presented here confirmed a new physiological role for CalR that acts as an activator for cpsQ-mfpABC and mfpABC transcription., (© 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

Vibrio parahaemolyticus is the leading cause of seafood-associated gastroenteritis. Type III secretion system 1 (T3SS1) is one of the virulence determinants of this bacteria. T3SS1 expression is regulated by ToxR and CalR. ToxR represses the transcription of T3SS1 genes via activation of CalR, which acts as a transcriptional repressor of T3SS1 genes. However, the transcriptional regulation mechanisms have not been elucidated. As showing in the present work, ToxR binds to the promoter DNA region of calR to activate its transcription. CalR occupies the promoter-proximal regions of each detected target operons in T3SS1 loci to repress their transcription, and thereby inhibiting T3SS1-dependent cytotoxicity. Moreover, a feedback CalR inhibits toxR and its own gene in a direct manner. Collectively, this work reported an interesting gene regulatory network involving the reciprocal regulation of ToxR and CalR, and their regulation on T3SS1 genes transcription in V. parahaemolyticus ., Competing Interests: CONFLICTS OF INTEREST The authors declare that no conflicts of interest exists.

Bacterial noncoding RNAs (ncRNA) regulate diverse cellular processes, including virulence and environmental fitness. The malS 5' untranslated region (named malS-5'UTR) was identified as a regulatory ncRNA that increases the invasive capacity of Salmonella enterica serovar Typhi. An IntaRNA search suggested base pairing between malS-5'UTR and hisG mRNA, a key gene in the histidine biosynthetic pathway. Overexpression of malS-5'UTR markedly reduced bacterial growth in minimal medium without histidine. Overexpression of malS-5'UTR increased mRNA from his operon genes, independently of the bax gene, and decreased HisG protein in Salmonella Typhi. RNA structure analysis showed base pairing of the malS-5'UTR RNA with the hisG mRNA across the ribosome binding site. Thus, we propose that malS-5'UTR inhibited hisG translation, probably by base pairing to the Shine-Dalgarno sequence.

Vibrio parahaemolyticus is a leading cause of seafood-associated diarrhea and gastroenteritis. This bacteria expresses a major virulence determinant called T3SS1. Expression of T3SS1 is tightly regulated by the ExsA-ExsC-ExsD regulatory system. The transcription of exsA and probably exsC is repressed directly by the H-NS protein. In this study, the regulation of exsD by H-NS was investigated using quantitative RT-PCR, primer extension, LacZ fusion, electrophoretic mobility shift, and DNase I footprinting assays. The results showed that His-H-NS protected a single region from 61 bp to 174 bp upstream of exsD against DNase I digestion, and a transcription start site located at 105 bp upstream of exsD was detected and its activity was repressed by H-NS. Therefore, a single H-NS-dependent promoter was transcribed for exsD in V. parahaemolyticus. Thus, all three genes in the ExsA-ExsC-ExsD regulatory system of T3SS1 are directly repressed by H-NS in V. parahaemolyticus., (Copyright © 2016 Elsevier Ltd. All rights reserved.)