16 results on '"Tanu Chawla"'
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2. Systemic inflammation, innate immunity and pathogenesis after Zika virus infection in cynomolgus macaques are modulated by strain-specificity within the Asian lineage
- Author
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Ruklanthi de Alwis, Raphaël M. Zellweger, Edmond Chua, Lin-Fa Wang, Tanu Chawla, October M. Sessions, Damien Marlier, John E. Connolly, Veronika von Messling, and Danielle E. Anderson
- Subjects
Zika virus ,flavivirus ,arbovirus ,NHP ,inflammation ,innate immunity ,Infectious and parasitic diseases ,RC109-216 ,Microbiology ,QR1-502 - Abstract
Zika virus (ZIKV) is an emerging arbovirus with recent global expansion. Historically, ZIKV infections with Asian lineages have been associated with mild disease such as rash and fever. However, recent Asian sub-lineages have caused outbreaks in the South Pacific and Latin America with increased prevalence of neurological disorders in infants and adults. Asian sub-lineage differences may partially explain the range of disease severity observed. However, the effect of Asian sub-lineage differences on pathogenesis remains poorly characterized. Current study conducts a head-to-head comparison of three Asian sub-lineages that are representative of the circulating ancestral mild Asian strain (ZIKV-SG), the 2007 epidemic French Polynesian strain (ZIKV-FP), and the 2013 epidemic Brazil strain (ZIKV-Brazil) in adult Cynomolgus macaques. Animals infected intervenously or subcutaneously with either of the three clinical isolates showed sub-lineage-specific differences in viral pathogenesis, early innate immune responses and systemic inflammation. Despite the lack of neurological symptoms in infected animals, the epidemiologically neurotropic ZIKV sub-lineages (ZIKV-Brazil and/or ZIKV-FP) were associated with more sustained viral replication, higher systemic inflammation (i.e. higher levels of TNFα, MCP-1, IL15 and G-CSF) and greater percentage of CD14+ monocytes and dendritic cells in blood. Multidimensional analysis showed clustering of ZIKV-SG away from ZIKV-Brazil and ZIKV-FP, further confirming sub-lineage differences in the measured parameters. These findings highlight greater systemic inflammation and monocyte recruitment as possible risk factors of adult ZIKV disease observed during the 2007 FP and 2013 Brazil epidemics. Future studies should explore the use of anti-inflammatory therapeutics as early treatment to prevent ZIKV-associated disease in adults.
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- 2021
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3. Structure mapping of dengue and Zika viruses reveals functional long-range interactions
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Roland G. Huber, Xin Ni Lim, Wy Ching Ng, Adelene Y. L. Sim, Hui Xian Poh, Yang Shen, Su Ying Lim, Karin B. Sundstrom, Xuyang Sun, Jong Ghut Aw, Horng Khit Too, Peng Hee Boey, Andreas Wilm, Tanu Chawla, Milly M. Choy, Lu Jiang, Paola Florez de Sessions, Xian Jun Loh, Sylvie Alonso, Martin Hibberd, Niranjan Nagarajan, Eng Eong Ooi, Peter J. Bond, October M. Sessions, and Yue Wan
- Subjects
Science - Abstract
Here, the authors provide detailed analyses of viral RNA structure in virions and in infected cells for four dengue virus serotypes and four Zika virus strains, and identify conserved structures that are important for virus replication.
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- 2019
- Full Text
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4. Presence of Recombinant Bat Coronavirus GCCDC1 in Cambodian Bats
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Feng Zhu, Veasna Duong, Xiao Fang Lim, Vibol Hul, Tanu Chawla, Lucy Keatts, Tracey Goldstein, Alexandre Hassanin, Vuong Tan Tu, Philippe Buchy, October M. Sessions, Lin-Fa Wang, Philippe Dussart, and Danielle E. Anderson
- Subjects
bats ,coronavirus ,GCCDC1 ,zoonosis ,recombination ,co-infection ,Microbiology ,QR1-502 - Abstract
Bats have been recognized as an exceptional viral reservoir, especially for coronaviruses. At least three bat zoonotic coronaviruses (SARS-CoV, MERS-CoV and SARS-CoV-2) have been shown to cause severe diseases in humans and it is expected more will emerge. One of the major features of CoVs is that they are all highly prone to recombination. An extreme example is the insertion of the P10 gene from reoviruses in the bat CoV GCCDC1, first discovered in Rousettus leschenaultii bats in China. Here, we report the detection of GCCDC1 in four different bat species (Eonycteris spelaea, Cynopterus sphinx, Rhinolophus shameli and Rousettus sp.) in Cambodia. This finding demonstrates a much broader geographic and bat species range for this virus and indicates common cross-species transmission. Interestingly, one of the bat samples showed a co-infection with an Alpha CoV most closely related to RsYN14, a virus recently discovered in the same genus (Rhinolophus) of bat in Yunnan, China, 2020. Taken together, our latest findings highlight the need to conduct active surveillance in bats to assess the risk of emerging CoVs, especially in Southeast Asia.
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- 2022
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- View/download PDF
5. Dengue virus activates cGAS through the release of mitochondrial DNA
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Bo Sun, Karin B. Sundström, Jun Jie Chew, Pradeep Bist, Esther S. Gan, Hwee Cheng Tan, Kenneth C. Goh, Tanu Chawla, Choon Kit Tang, and Eng Eong Ooi
- Subjects
Medicine ,Science - Abstract
Abstract Cyclic GMP-AMP synthetase (cGAS) is a DNA-specific cytosolic sensor, which detects and initiates host defense responses against microbial DNA. It is thus curious that a recent study identified cGAS as playing important roles in inhibiting positive-sense single-stranded RNA (+ssRNA) viral infection, especially since RNA is not known to activate cGAS. Using a dengue virus serotype 2 (DENV-2) vaccine strain (PDK53), we show that infection creates an endogenous source of cytosolic DNA in infected cells through the release of mitochondrial DNA (mtDNA) to drive the production of cGAMP by cGAS. Innate immune responses triggered by cGAMP contribute to limiting the spread of DENV to adjacent uninfected cells through contact dependent gap junctions. Our result thus supports the notion that RNA virus indirectly activates a DNA-specific innate immune signaling pathway and highlights the breadth of the cGAS-induced antiviral response.
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- 2017
- Full Text
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6. Application of a targeted-enrichment methodology for full-genome sequencing of Dengue 1-4, Chikungunya and Zika viruses directly from patient samples.
- Author
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Uma Sangumathi Kamaraj, Jun Hao Tan, Ong Xin Mei, Louise Pan, Tanu Chawla, Anna Uehara, Lin-Fa Wang, Eng Eong Ooi, Duane J Gubler, Hasitha Tissera, Lee Ching Ng, Annelies Wilder-Smith, Paola Florez de Sessions, Timothy Barkham, Danielle E Anderson, and October Michael Sessions
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
The frequency of epidemics caused by Dengue viruses 1-4, Zika virus and Chikungunya viruses have been on an upward trend in recent years driven primarily by uncontrolled urbanization, mobility of human populations and geographical spread of their shared vectors, Aedes aegypti and Aedes albopictus. Infections by these viruses present with similar clinical manifestations making them challenging to diagnose; this is especially difficult in regions of the world hyperendemic for these viruses. In this study, we present a targeted-enrichment methodology to simultaneously sequence the complete viral genomes for each of these viruses directly from clinical samples. Additionally, we have also developed a customized computational tool (BaitMaker) to design these enrichment baits. This methodology is robust in its ability to capture diverse sequences and is amenable to large-scale epidemiological studies. We have applied this methodology to two large cohorts: a febrile study based in Colombo, Sri Lanka taken during the 2009-2015 dengue epidemic (n = 170) and another taken during the 2016 outbreak of Zika virus in Singapore (n = 162). Results from these studies indicate that we were able to cover an average of 97.04% ± 0.67% of the full viral genome from samples in these cohorts. We also show detection of one DENV3/ZIKV co-infected patient where we recovered full genomes for both viruses.
- Published
- 2019
- Full Text
- View/download PDF
7. Dengue virus neutralization in cells expressing Fc gamma receptors.
- Author
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Tanu Chawla, Kuan Rong Chan, Summer L Zhang, Hwee Cheng Tan, Angeline P C Lim, Brendon J Hanson, and Eng Eong Ooi
- Subjects
Medicine ,Science - Abstract
Activating Fc gamma receptors (FcγRs) in hematopoietic cells serve to remove antibody-opsonized antigens, including dengue virus (DENV), from systemic circulation. While neutralizing antibody concentrations provide humoral immunity, cross-reactive or sub-neutralizing levels of antibody can result in antibody-dependent enhancement of DENV infection that increases overall viral burden. Recently, it has been suggested that the antibody levels needed for DENV neutralization differs when different FcγR is engaged. If this is true, the threshold titer used to infer immunity should be influenced by FcγR usage. Here, using cells that express both activating and inhibitory FcγRs, we show that the type of FcγR engaged during phagocytosis can influence the antibody concentration requirement for DENV neutralization. We demonstrate that phagocytosis through FcγRI requires significantly less antibody for complete DENV neutralization compared to FcγRIIA. Furthermore, when DENV is opsonized with sub-neutralizing levels of antibody, FcγRI-mediated phagocytosis resulted in significantly reduced DENV titers compared to FcγRIIA. However, while FcγRI may remove antibody-opsonized DENV more efficiently, this receptor is only preferentially engaged by clustering when neutralizing, but not sub-neutralizing antibody concentrations, were used. Collectively, our study demonstrates that activating FcγR usage may influence antibody titers needed for DENV neutralization.
- Published
- 2013
- Full Text
- View/download PDF
8. Structure mapping of dengue and Zika viruses reveals functional long-range interactions
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Lu Jiang, October M. Sessions, Anna Karin Beatrice Sundstrom, Jong Ghut Aw, Xin Ni Lim, Andreas Wilm, Eng Eong Ooi, Tanu Chawla, Xian Jun Loh, Roland G. Huber, Hui Xian Poh, Milly M. Choy, Peng Hee Boey, Yang Shen, Adelene Y. L. Sim, Horng Khit Too, Peter J. Bond, Yue Wan, Niranjan Nagarajan, Su Ying Lim, Martin L. Hibberd, Paola Florez de Sessions, Sylvie Alonso, Xuyang Sun, Wy Ching Ng, and School of Biological Sciences
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Models, Molecular ,0301 basic medicine ,viruses ,Science ,General Physics and Astronomy ,Genome, Viral ,02 engineering and technology ,Dengue virus ,medicine.disease_cause ,Genome ,Article ,General Biochemistry, Genetics and Molecular Biology ,Cell Line ,Conserved sequence ,Zika virus ,Dengue fever ,Mice ,03 medical and health sciences ,Flaviviridae ,medicine ,Animals ,Humans ,lcsh:Science ,Conserved Sequence ,Genetics ,Multidisciplinary ,Base Sequence ,biology ,Nicotinic Acids ,Virion ,Chromosome Mapping ,RNA ,Biological sciences [Science] ,General Chemistry ,Zika Virus ,Dengue Virus ,021001 nanoscience & nanotechnology ,biology.organism_classification ,medicine.disease ,Flavivirus ,030104 developmental biology ,Mutation ,RNA, Viral ,lcsh:Q ,0210 nano-technology - Abstract
Dengue (DENV) and Zika (ZIKV) viruses are clinically important members of the Flaviviridae family with an 11 kb positive strand RNA genome that folds to enable virus function. Here, we perform structure and interaction mapping on four DENV and ZIKV strains inside virions and in infected cells. Comparative analysis of SHAPE reactivities across serotypes nominates potentially functional regions that are highly structured, conserved, and contain low synonymous mutation rates. Interaction mapping by SPLASH identifies many pair-wise interactions, 40% of which form alternative structures, suggesting extensive structural heterogeneity. Analysis of shared interactions between serotypes reveals a conserved macro-organization whereby interactions can be preserved at physical locations beyond sequence identities. We further observe that longer-range interactions are preferentially disrupted inside cells, and show the importance of new interactions in virus fitness. These findings deepen our understanding of Flavivirus genome organization and serve as a resource for designing therapeutics in targeting RNA viruses., Here, the authors provide detailed analyses of viral RNA structure in virions and in infected cells for four dengue virus serotypes and four Zika virus strains, and identify conserved structures that are important for virus replication.
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- 2019
9. Dengue virus activates cGAS through the release of mitochondrial DNA
- Author
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Jun Jie Chew, Kenneth C. Goh, Tanu Chawla, Hwee Cheng Tan, Pradeep Bist, Bo Sun, Choon Kit Tang, Eng Eong Ooi, Esther S. Gan, and Karin B. Sundstrom
- Subjects
0301 basic medicine ,Mitochondrial DNA ,Microbial DNA ,Science ,Dengue virus ,medicine.disease_cause ,DNA, Mitochondrial ,Article ,Cell Line ,03 medical and health sciences ,chemistry.chemical_compound ,Immunity ,Cricetinae ,medicine ,Animals ,Humans ,Receptors, Immunologic ,Multidisciplinary ,Innate immune system ,biology ,RNA ,RNA virus ,Epithelial Cells ,Dengue Virus ,biology.organism_classification ,Virology ,Nucleotidyltransferases ,Immunity, Innate ,030104 developmental biology ,chemistry ,Medicine ,DNA - Abstract
Cyclic GMP-AMP synthetase (cGAS) is a DNA-specific cytosolic sensor, which detects and initiates host defense responses against microbial DNA. It is thus curious that a recent study identified cGAS as playing important roles in inhibiting positive-sense single-stranded RNA (+ssRNA) viral infection, especially since RNA is not known to activate cGAS. Using a dengue virus serotype 2 (DENV-2) vaccine strain (PDK53), we show that infection creates an endogenous source of cytosolic DNA in infected cells through the release of mitochondrial DNA (mtDNA) to drive the production of cGAMP by cGAS. Innate immune responses triggered by cGAMP contribute to limiting the spread of DENV to adjacent uninfected cells through contact dependent gap junctions. Our result thus supports the notion that RNA virus indirectly activates a DNA-specific innate immune signaling pathway and highlights the breadth of the cGAS-induced antiviral response.
- Published
- 2017
10. Application of a targeted-enrichment methodology for full-genome sequencing of Dengue 1-4, Chikungunya and Zika viruses directly from patient samples
- Author
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Lee Ching Ng, Jun Hao Tan, Tanu Chawla, Annelies Wilder-Smith, Duane J. Gubler, Eng Eong Ooi, Ong Xin Mei, Danielle E. Anderson, Lin-Fa Wang, Uma S. Kamaraj, Timothy Barkham, Hasitha Tissera, Anna Uehara, October M. Sessions, Louise Pan, Paola Florez de Sessions, Messer, William B., and Lee Kong Chian School of Medicine (LKCMedicine)
- Subjects
RNA viruses ,0301 basic medicine ,Molecular biology ,viruses ,RC955-962 ,Dengue virus ,Pathology and Laboratory Medicine ,medicine.disease_cause ,Genome ,Disease Outbreaks ,Zika virus ,Dengue fever ,Dengue ,Database and Informatics Methods ,0302 clinical medicine ,DNA library construction ,Arctic medicine. Tropical medicine ,Medicine and Health Sciences ,Science::Medicine [DRNTU] ,Chikungunya ,Singapore ,Viral Genomics ,Chikungunya Virus ,biology ,Coinfection ,Zika Virus Infection ,High-Throughput Nucleotide Sequencing ,Genomics ,Genomic Library Construction ,3. Good health ,Infectious Diseases ,Medical Microbiology ,Viral Pathogens ,Viruses ,Viral Genome ,Pathogens ,Public aspects of medicine ,RA1-1270 ,Nucleic Acid Amplification Techniques ,Sequence Analysis ,Research Article ,Aedes albopictus ,Bioinformatics ,Alphaviruses ,030231 tropical medicine ,Sequence Databases ,Genome, Viral ,Microbial Genomics ,Aedes aegypti ,DNA construction ,Microbiology ,Cell Line ,Togaviruses ,03 medical and health sciences ,Virology ,Genetics ,medicine ,Humans ,Microbial Pathogens ,Sri Lanka ,Flaviviruses ,Organisms ,Public Health, Environmental and Occupational Health ,Computational Biology ,Biology and Life Sciences ,Outbreak ,Zika Virus ,Dengue Virus ,Genome Analysis ,biology.organism_classification ,medicine.disease ,Genomic Libraries ,Research and analysis methods ,Molecular biology techniques ,Biological Databases ,030104 developmental biology ,Chikungunya Fever - Abstract
The frequency of epidemics caused by Dengue viruses 1–4, Zika virus and Chikungunya viruses have been on an upward trend in recent years driven primarily by uncontrolled urbanization, mobility of human populations and geographical spread of their shared vectors, Aedes aegypti and Aedes albopictus. Infections by these viruses present with similar clinical manifestations making them challenging to diagnose; this is especially difficult in regions of the world hyperendemic for these viruses. In this study, we present a targeted-enrichment methodology to simultaneously sequence the complete viral genomes for each of these viruses directly from clinical samples. Additionally, we have also developed a customized computational tool (BaitMaker) to design these enrichment baits. This methodology is robust in its ability to capture diverse sequences and is amenable to large-scale epidemiological studies. We have applied this methodology to two large cohorts: a febrile study based in Colombo, Sri Lanka taken during the 2009–2015 dengue epidemic (n = 170) and another taken during the 2016 outbreak of Zika virus in Singapore (n = 162). Results from these studies indicate that we were able to cover an average of 97.04% ± 0.67% of the full viral genome from samples in these cohorts. We also show detection of one DENV3/ZIKV co-infected patient where we recovered full genomes for both viruses., Author summary Dengue viruses 1–4 (DENV1-4), Zika virus (ZIKV) and Chikungunya virus (CHIKV) are tropical and subtropical viruses that share a common arthropod vector, and have very similar clinical presentations that are difficult to distinguish. With the recent outbreaks of DENV, ZIKV and CHIKV globally, a single methodology able to simultaneously distinguish these viruses and provide full-genome information would greatly increase our capacity to rapidly characterize outbreaks. As a proof of principle, we have applied this methodology to two large cohorts in Sri Lanka and Singapore taken during recent dengue and Zika outbreaks, respectively. Herein, we present the results of this application to these cohorts and provide the tools to replicate these methodologies for other cohorts.
- Published
- 2019
11. Dengue: An Expanding Neglected Tropical Disease
- Author
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Tanu Chawla, Annelies Wilder-Smith, and Eng Eong Ooi
- Subjects
business.industry ,Tropical disease ,International health ,medicine.disease ,World health ,Dengue fever ,Geography ,Environmental health ,Urbanization ,medicine ,Population growth ,Serostatus ,business ,Dengue vaccine - Abstract
The World Health Origanization has classified dengue as a major international public health concern. The reasons for the resurgence are complex, and are likely a combination of multiple factors, including population growth associated with rapid uncontrolled urbanization, increased movement of viruses in people among countries and regions via international travel, demographic changes, poor vector control, genetic changes in circulating or introduced viruses, and modulating climatic factors. The past decade has seen more investment in vaccine development and novel vector control measures than ever before. Three dengue vaccine candidates are far advanced in development, with CYD-TDV being the first licensed dengue vaccine. However, this vaccine showed serostatus dependent performance. The two other dengue vaccines are currently in Phase 3 efficacy trials.
- Published
- 2019
12. Structure mapping of dengue and Zika viruses reveals new functional long-range interactions
- Author
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Xuyang Sun, Roland G. Huber, Eng Eong Ooi, Paola Florez de Sessions, Xin Ni Lim, Andreas Wilm, Horng Khit Too, Jong Ghut Aw, Su Ying Lim, Lu Jiang, Hui Xian Poh, Xian Jun Loh, Peter J. Bond, Peng Hee Boey, October M. Sessions, Sylvie Alonso, Wy Ching Ng, Milly M. Choy, Anna Karin Beatrice Sundstrom, Yang Shen, Tanu Chawla, Adelene Y. L. Sim, Niranjan Nagarajan, Yue Wan, and Martin L. Hibberd
- Subjects
Silent mutation ,Genetics ,biology ,RNA ,Helicase ,Genomics ,biology.organism_classification ,medicine.disease ,Genome ,Virus ,Dengue fever ,Flaviviridae ,medicine ,biology.protein - Abstract
Dengue and Zika are clinically important members of the Flaviviridae family that utilizes an 11kb positive strand RNA for genome regulation. While structures have been mapped primarily in the UTRs, much remains to be learnt about how the rest of the genome folds to enable function. Here, we performed secondary structure and pair-wise interaction mapping on four dengue serotypes and four Zika strains in their native virus particles and infected cells. Comparative analysis of SHAPE reactivities across serotypes nominated potentially functional regions that are highly structured, show structure conservation, and low synonymous mutation rates, including a structure associated with ribosome pausing. Pair-wise interaction mapping by SPLASH further reveals new pair-wise interactions, in addition to the known circularization sequence. 40% of pair-wise interactions form alternative structures, suggesting extensive structural heterogeneity. Analysis of shared pair-wise interactions between serotypes revealed macro-organization whereby interactions are preserved at their physical locations, beyond their sequence identities. In addition, structure mapping of virus genomes released in solution-as well as inside host cells-showed that other helicases, in addition to the ribosome, play a role in unwinding viral structures inside cells. Mutational experiments that disrupt in cell and in virion pair-wise interactions result in virus attenuation, demonstrating their importance during the virus life-cycle.
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- 2018
- Full Text
- View/download PDF
13. Adenovirus-vectored vaccines
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Navin Khanna, Sathyamangalam Swaminathan, and Tanu Chawla
- Subjects
Pharmacology ,0303 health sciences ,business.industry ,viruses ,Immunogenicity ,Patent literature ,General Medicine ,Virology ,3. Good health ,Adenovirus vaccine ,03 medical and health sciences ,0302 clinical medicine ,Drug Discovery ,Medicine ,030212 general & internal medicine ,business ,030304 developmental biology ,medicine.drug - Abstract
Background: Engineered adenoviruses are being increasingly explored as immunoprophylactic or immunotherapeutic vaccine vectors. Encouraging data from preclinical studies using human adenovirus vectors carrying different antigen genes have resulted in many currently ongoing clinical trials. Objective: The article seeks to review the current status of the use of adenoviruses as vaccine vectors. Methods: This review is based on the patent literature since 2000 pertaining to the development of adenovirus vaccine vectors for infectious and non-infectious diseases. Conclusion: Human adenovirus-vectored vaccines have important limitations that stem from their immunogenicity and restrict their utility. This has spurred intensive efforts to find alternative adenovirus vectors and strategies, each with its own advantages and shortcomings.
- Published
- 2008
14. Replication in Mobile Ad-hoc Network using Hopfield Network
- Author
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Mukesh Kumar and Tanu Chawla
- Subjects
Hopfield network ,Routing protocol ,Vehicular ad hoc network ,Optimized Link State Routing Protocol ,Adaptive quality of service multi-hop routing ,business.industry ,Wireless ad hoc network ,Computer science ,Distributed computing ,Node (computer science) ,Mobile ad hoc network ,business ,Computer network - Abstract
Mobile Ad hoc Network (MANET) is a network comprises of mobile nodes connected without any centralized administration. Each node in the network has the ability to share a large number of objects with other nodes. The nodes are connected with other nodes to forward a message to other nodes until the search for node that desire meets. This paper represents a new replication method to recover the performance in distributed system. Objects are replicated on different nodes in the network to minimize the search for an object. It is observed that mobility of nodes predicted using SOM (Self Organizing Maps) technique provides less accuracy. This paper represents an algorithm that uses the network parameters as input condition to replicate objects into the nodes. The decision for each node will be taken by gathering the input conditions and feed to the Hopfield Neural Network. It is view that it will provide more accuracy and improve the performance.
- Published
- 2013
15. Dengue virus neutralization in cells expressing Fc gamma receptors
- Author
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Angeline P.C. Lim, Tanu Chawla, Hwee Cheng Tan, Kuan Rong Chan, Brendon J. Hanson, Summer L. Zhang, and Eng Eong Ooi
- Subjects
Viral Diseases ,viruses ,Blotting, Western ,Immunology ,lcsh:Medicine ,Viral Plaque Assay ,Microbiology ,Neutralization ,Cell Line ,Dengue Fever ,Dengue ,Antigen ,Phagocytosis ,Neutralization Tests ,Animals ,Humans ,RNA, Small Interfering ,Neutralizing antibody ,lcsh:Science ,Opsonin ,Biology ,Multidisciplinary ,biology ,Receptors, IgG ,lcsh:R ,Antibody titer ,Immunity ,virus diseases ,Dengue Virus ,biochemical phenomena, metabolism, and nutrition ,Flow Cytometry ,Virology ,Antibodies, Neutralizing ,Immune complex ,Infectious Diseases ,Humoral immunity ,Humoral Immunity ,biology.protein ,Medicine ,Clinical Immunology ,lcsh:Q ,Antibody ,Research Article ,Neglected Tropical Diseases - Abstract
Activating Fc gamma receptors (FcγRs) in hematopoietic cells serve to remove antibody-opsonized antigens, including dengue virus (DENV), from systemic circulation. While neutralizing antibody concentrations provide humoral immunity, cross-reactive or sub-neutralizing levels of antibody can result in antibody-dependent enhancement of DENV infection that increases overall viral burden. Recently, it has been suggested that the antibody levels needed for DENV neutralization differs when different FcγR is engaged. If this is true, the threshold titer used to infer immunity should be influenced by FcγR usage. Here, using cells that express both activating and inhibitory FcγRs, we show that the type of FcγR engaged during phagocytosis can influence the antibody concentration requirement for DENV neutralization. We demonstrate that phagocytosis through FcγRI requires significantly less antibody for complete DENV neutralization compared to FcγRIIA. Furthermore, when DENV is opsonized with sub-neutralizing levels of antibody, FcγRI-mediated phagocytosis resulted in significantly reduced DENV titers compared to FcγRIIA. However, while FcγRI may remove antibody-opsonized DENV more efficiently, this receptor is only preferentially engaged by clustering when neutralizing, but not sub-neutralizing antibody concentrations, were used. Collectively, our study demonstrates that activating FcγR usage may influence antibody titers needed for DENV neutralization.
- Published
- 2013
16. The prevalence of antibodies to adenovirus serotype 5 in an adult Indian population and implications for adenovirus vector vaccines
- Author
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Navin Khanna, Tanu Chawla, Rajendra Pilankatta, and Sathyamangalam Swaminathan
- Subjects
Serotype ,Adult ,Male ,Genetic Vectors ,India ,Blood Donors ,Biology ,medicine.disease_cause ,Antibodies, Viral ,Virus ,Viral vector ,Cell Line ,Adenovirus Infections, Human ,Blood serum ,Neutralization Tests ,Seroepidemiologic Studies ,Virology ,medicine ,Animals ,Humans ,Vector (molecular biology) ,Adenoviruses, Human ,Middle Aged ,Virus Internalization ,biology.organism_classification ,Antibodies, Neutralizing ,Antibody-Dependent Enhancement ,Adenoviridae ,Mastadenovirus ,Infectious Diseases ,biology.protein ,Female ,Antibody - Abstract
In vivo gene delivery using human adenovirus serotype 5 (AdV5) vectors is being explored for vaccination purposes. The presence of anti-AdV5 antibodies in human serum arising from natural exposure to AdV5 can interfere potentially with and compromise the efficacy of rAdV5-based vaccine vectors. In this report, a collection of 114 sera from healthy adult Indian blood donors was analyzed for the presence of anti-AdV5 antibodies, using an AdV5 vector encoding the green fluorescent protein (GFP) to monitor the presence of anti-AdV5 neutralizing antibodies in human sera based on their ability to block virus entry into HeLa cells which express the Coxsackievirus-and-Adenovirus Receptor (CAR). In this assay all samples tested were positive for anti-AdV5 antibodies, with titers varying over a very wide range. It was also observed that these antibodies facilitated the uptake of the reporter AdV5 vector into the monocytic cell line U937 which does not express CAR, but expresses Fc receptors (FcRs) instead. These observations have implications for rAdV5-based vaccine development. J. Med. Virol. 82:407-414, 2010. (c) 2010 Wiley-Liss, Inc.
- Published
- 2010
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