Publications by authors named "Murugesan Amudhan"

The decline in dengue incidence and/or prevalence during the COVID-19 pandemic (2020-22) appears to be attributed to reduced treatment-seeking rates, under-reporting, misdiagnosis, disrupted health services and reduced exposure to mosquito vectors due to prevailing lockdowns. There is limited scientific data on dengue virus (DENV) disease during the COVID-19 pandemic. Here, we conducted a community-based, cross-sectional, cluster-randomized survey to assess anti-DENV and anti-SARS-CoV-2 seroprevalence, and also estimated the spatial distribution of DENV-positive aedine mosquito vectors during the COVID-19 pandemic across all the 38 districts of Tamil Nadu, India.

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In December 2023, we observed a notable shift in the COVID-19 landscape, when JN.1 omicron emerged as the predominant SARS-CoV-2 variant with a 95% incidence. We characterized the clinical profile, and genetic changes in JN.

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Introduction: The coronavirus disease 2019 (COVID-19) is a viral infection characterized by respiratory and gastrointestinal symptoms. The causative agent of this infection is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The genomic study helps in understanding the pathogenesis, epidemiology, and the development of therapeutic and preventive strategies in the combat against COVID-19.

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Background: Dengue is a vector-borne viral disease impacting millions across the globe. Nevertheless, akin to many other diseases, reports indicated a decline in dengue incidence and seroprevalence during the COVID-19 pandemic (2020-22). This presumably could be attributed to reduced treatment-seeking rates, under-reporting, misdiagnosis, disrupted health services and reduced exposure to vectors due to lockdowns.

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Human pegivirus (HPgV) appears to alter the prognosis of HIV disease by modulating T cell homeostasis, chemokine/cytokine production, and T cell activation. In this study, we evaluated if HPgV had any 'favorable' impact on the quantity and quality of T cells in HIV-infected individuals. T cell subsets such as CD4, CD4, and CD8 T cells, CD4 MAIT cells, CD8 MAIT cells, follicular helper T (TFH) cells, and follicular cytotoxic T (TFC) cells were characterized based on the expression of markers associated with immune activation (CD69, ICOS), proliferation (ki67), cytokine production (TNF-α, IFN-γ), and exhaustion (PD-1).

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In December 2023, we observed a notable shift in the COVID-19 landscape, when the JN.1 emerged as a predominant SARS-CoV-2 variant with a 95% incidence. We characterized the clinical profile, and genetic changes in JN.

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Background: Chronic viral infection results in impaired immune responses rendering viral persistence. Here, we compared the quality of T-cell responses among chronic hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV)-infected individuals by examining the levels of expression of selected immune activation and exhaustion molecules on circulating MAIT cells and Tfh cells.

Methods: Cytokines were measured using a commercial Bio-plex Pro Human Cytokine Grp I Panel 17-plex kit (BioRad, Hercules, CA, USA).

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Article Synopsis
  • - The study investigated the role and mutations of the XBB omicron variant in COVID-19 cases among hospitalized patients in Tamil Nadu, India, particularly in the context of increased breakthrough infections despite vaccination efforts.
  • - Researchers analyzed nasopharyngeal and oropharyngeal swabs from 98 patients using real-time PCR and Next Generation Sequencing, identifying 43 mutations in the S gene, including two new mutations, A27S and T747I, which had not been previously reported.
  • - The findings suggested that factors such as age and underlying health conditions were more critical in susceptibility to infection than vaccination status, with XBB.3 being the main variant identified among vaccinated individuals experiencing breakthrough infections.
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Early detection of latent tuberculosis infection (LTBI) is critical to TB elimination in the current WHO vision of End Tuberculosis Strategy. The study investigates whether detecting plasma cytokines could aid in diagnosing LTBI across household contacts (HHCs) positive for IGRA, HHCs negative for IGRA, and healthy controls. The plasma cytokines were measured using a commercial Bio-Plex Pro Human Cytokine 17-plex assay.

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Background: Early detection of latent tuberculosis infection (LTBI) is critical to TB elimination in the current WHO vision of .

Methods: We investigated whether detecting plasma cytokines could aid in diagnosing LTBI across household contacts (HHCs) positive for IGRA, HHCs negative for IGRA, and healthy controls. We also measured the plasma cytokines using a commercial assay.

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Chronic viral infection results in impaired immune responses rendering viral persistence. Here, we investigated the role of immune activation and compared the quality of T-cell responses in chronic HBV, HCV, and HIV infections. Cytokines were measured using a commercial Bio-plex Pro Human Cytokine Grp I Panel 17-plex kit (BioRad, Hercules, CA, USA).

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Chronic viral infections represent a leading cause of global morbidity and mortality. Chronic HBV, HCV, and HIV infections result in cytokine perturbations that may hold key implications in understanding the complex disease mechanisms driving virus persistence and/or resolution. Here, we determined the levels of various plasma cytokines using a commercial Bio-Plex Luminex cytokine array in chronic HBV ( = 30), HCV ( = 15), and HIV ( = 40) infections and correlated with corresponding plasma viral loads (PVLs) and liver parameters.

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Article Synopsis
  • Scientific research suggests that human pegivirus (HPgV) might help slow down the progression of HIV and is typically not linked to liver issues.
  • In a study, HIV-infected individuals with HPgV showed lower plasma viral loads and better liver health compared to those without HPgV.
  • HPgV-positive participants also had higher interleukin-7 levels and better CD4+ T cell counts, indicating a potential positive effect on HIV disease markers.
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The rapid spread of SARS-CoV-2 variants in the global population is indicative of the development of selective advantages in emerging virus strains. Here, we performed a case-control investigation of the clinical and demographic characteristics, clinical history, and virological markers to predict disease progression in hospitalized adults for COVID-19 between December 2021 and January 2022 in Chennai, India. COVID-19 diagnosis was made by a commercial TaqPath COVID-19 RT-PCR, and WGS was performed with the Ion Torrent Next Generation Sequencing System.

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Background: Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) kits have been reliably employed for the diagnosis of coronavirus disease 2019 (COVID-19) by the detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA since the beginning of the disease outbreak. In consideration of reliable diagnosis, apart from RT-PCR, the isothermal nucleic acid amplification-based point-of-care automated kits have also been tagged as a simpler and rapid alternative to the conventional techniques. Currently, the availability of a better diagnostic method for COVID-19 when compared to RT-PCR is nil.

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Mucosal-associated invariant T (MAIT) cells are a unique subset of innate-like T cells that bridge between innate and adaptive immunity. MAIT cells act like a 'biliary firewall' protecting the epithelial lining of the liver against pathogenic intruders. MAIT1 and MAIT17 subsets respond rapidly to pathogenic presence both in the liver as well as in the peripheral circulation.

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Background: Dengue fever (DF) is caused by an arthropod-borne dengue virus (DENV), has four serotypes and several genotypes. Although having clinical and epidemiological significance, the information on the circulating serotypes/genotypes is scarce in India.

Materials And Methods: Blood specimens were collected from the patients suspected of DF and they are tested for DENV NS1 antigen and DENV IgM by ELISA.

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Peripheral follicular helper T (pTfh) cells represent specialized CD4 T cells that help B cells to secrete antibodies. Dengue infection appears to cause immune activation in a wide array of immune cells. Herein, we investigated the signatures of immune activation of circulating Tfh cells and mucosal-associated invariant T (MAIT) cells in adult subjects with confirmed acute clinical dengue virus (DENV) infection by multiparametric flow cytometry.

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Mucosa-associated invariant T (MAIT) cells are recently characterized as a novel subset of innate-like T cells that recognize microbial metabolites as presented by the MHC-1b-related protein MR1. The significance of MAIT cells in anti-bacterial defense is well-understood but not clear in viral infections such as SIV/HIV infection. Here we studied the phenotype, distribution, and function of MAIT cells and their association with plasma viral levels during chronic SHIV infection in rhesus macaques (RM).

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Dengue virus (DENV) infection has become an increasingly common concern in tropical and subtropical regions. It has protean manifestations ranging from febrile phase to severe life-threatening illness. In this study, we estimated Th1 and Th2 cytokines and correlated the levels with dengue severity along with certain hematological and biochemical parameters.

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Objectives: The emergence and dissemination of carbapenem-resistant Enterobacteriaceae (CRE) is an important public health problem. This study aimed to understand the prevalence and mechanisms of carbapenem resistance in clinically important members of Enterobacteriaceae in rural South India.

Methods: Routine clinical isolates of Escherichia coli and Klebsiella spp.

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Objective: To investigate the role of genotypic and phenotypic characteristics of killer cell immunoglobulin-like receptors (KIRs) and their human leukocyte antigen (HLA) class-1 ligands in HIV-1 disease progression.

Study Design And Methods: This is a nested case-control study including 347 HIV seropositive (HIV-1+) individuals from South India constituting 45 long-term nonprogressors (LTNPs) and 302 disease progressors. KIR genotyping was performed by multiplex sequence-specific primer-directed PCR (SSP-PCR).

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Mucosal-associated invariant T (MAIT) cells, defined as CD161TCR iVα7.2 T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection.

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