Next-Gen Dual Transcriptomics for Adult Extrapulmonary Tuberculosis Biomarkers and Host-Pathogen Interplay in Human Cells: A Strategic Review.

Tuberculosis (TB) is a major public health concern that results in significant morbidity and mortality, particularly in middle- to low-income countries. Extra-pulmonary tuberculosis (EPTB) in adults is a form of TB that affects organs other than the lungs and is challenging to diagnose and treat due to a lack of accurate early diagnostic markers and inadequate knowledge of host immunity. Next-generation sequencing-based approaches have shown potential for identifying diagnostic biomarkers and host immune responses related to EPTB. This strategic review discusses on the significance using primary human cells and cell lines for in vitro transcriptomic studies on common forms of EPTB, such as lymph node TB, brain TB, bone TB, and endometrial TB to derive potential insights. While organoids have shown promise as a model system, primary cell lines still remain a valuable tool for studying host-pathogen interplay due to their conserved immune system, non-iPSC origin, and lack of heterogeneity in cell population. This review outlines a basic workflow for researchers interested in performing transcriptomics studies in EPTB, and also discusses the potential of cell-line based dual RNA-Seq technology for deciphering comprehensive transcriptomic signatures, host-pathogen interplay, and biomarkers from the host and Mycobacterium tuberculosis. Thus, emphasizing the implementation of this technique which can significantly contribute to the global anti-TB effort and advance our understanding of EPTB.

Comparison of Real-time RT-PCR cycle threshold (Ct) values with clinical features and severity of COVID-19 disease among hospitalized patients in the first and second waves of COVID-19 pandemic in Chennai, India.

Introduction: Real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) of nasopharyngeal/ oropharyngeal swab has been the gold standard test for detection of SARS-CoV-2 infection The relationship between cycle threshold (Ct) values of rRT-PCR and severity of disease remain disputable and not clearly defined in COVID-19. Methodology: This is a single-centered retrospective observational study conducted at Government Corona Hospital (GCH), Guindy, Chennai. In the present study, we compared the Ct value of rRT-PCR from nasopharyngeal swab specimens with a diverse range of symptoms and disease severity among 240 individuals who were hospitalized with COVID-19, viz., mild cases (MC; n = 160), moderately severe cases (MSC; n = 46) and severe cases (SC; n = 34) in the first and second waves of COVID-19 pandemic. Results: The study included 240 hospitalized COVID-19 patients with a median age of 52 years (range 21 to 90 years). MC, MSC, and SC all had median Ct values of 25.0 (interquartile range - IQR 20.0 to 30.5), 29.5 (IQR 23.0 to 34.0), and 29.0 (IQR 24 to 37.5) for the ORF1ab gene. The Ct value differed significantly between mild vs moderate, and mild vs severe cases. The Ct value of SC group with co-morbidity of type 2 diabetes have a significant difference compared to non-diabetes group (p value <0.05). There was a significant difference in the median Ct value of ORF1ab gene among the MSC group and MC but not in the SC group in the first and second waves of the pandemic (p<0.05). Conclusion: We conclude that SARS-CoV-2 Ct values of rRT-PCR alone does not have a role in aiding severity stratification among patients with COVID-19 since the viral dynamics and Ct value may vary due to the emerging variants that occur in different waves of the pandemic.

Pooled Testing Strategies for SARS-CoV-2 diagnosis: A comprehensive review.

SARS-CoV-2 has surged across the globe causing the ongoing COVID-19 pandemic. Systematic testing to facilitate index case isolation and contact tracing is needed for efficient containment of viral spread. The major bottleneck in leveraging testing capacity has been the lack of diagnostic resources. Pooled testing is a potential approach that could reduce cost and usage of test kits. This method involves pooling individual samples and testing them 'en bloc'. Only if the pool tests positive, retesting of individual samples is performed. Upon reviewing recent articles on this strategy employed in various SARS-CoV-2 testing scenarios, we found substantial diversity emphasizing the requirement of a common protocol. In this article, we review various theoretically simulated and clinically validated pooled testing models and propose practical guidelines on applying this strategy for large scale screening. If implemented properly, the proposed approach could contribute to proper utilization of testing resources and flattening of infection curve.

Evaluation of antiviral T cell responses and TSCM cells in volunteers enrolled in a phase I HIV-1 subtype C prophylactic vaccine trial in India.

T cells play an important role in controlling viral replication during HIV infection. An effective vaccine should, therefore, lead to the induction of a strong and early viral-specific CD8+ T cell response. While polyfunctional T cell responses are thought to be important contributors to the antiviral response, there is evidence to show that polyfunctional HIV- specific CD8+ T cells are just a small fraction of the total HIV-specific CD8+ T cells and may be absent in many individuals who control HIV replication, suggesting that other HIV-1 specific CD8+ effector T cell subsets may be key players in HIV control. Stem cell-like memory T cells (TSCM) are a subset of T cells with a long half-life and self-renewal capacity. They serve as key reservoirs for HIV and contribute a significant barrier to HIV eradication. The present study evaluated vaccine-induced antiviral responses and TSCM cells in volunteers vaccinated with a subtype C prophylactic HIV-1 vaccine candidate administered in a prime-boost regimen. We found that ADVAX DNA prime followed by MVA boost induced significantly more peripheral CD8+ TSCM cells and higher levels of CD8+ T cell-mediated inhibition of replication of different HIV-1 clades as compared to MVA alone and placebo. These findings are novel and provide encouraging evidence to demonstrate the induction of TSCM and cytotoxic immune responses by a subtype C HIV-1 prophylactic vaccine administered using a prime-boost strategy.

Transmitted HIV-1 Drug Resistance in a Treatment-Naive Cohort of Recently Infected Individuals from Chennai, India.

A cross-sectional study was undertaken to examine the prevalence and pattern of HIV drug resistance mutations (DRMs) among recently HIV-1-infected and antiretroviral therapy (ART)-naive individuals from Chennai, South India. The HIV-1 pol gene encompassing the protease and reverse transcriptase (RT) regions were analyzed from 53 ART-naive HIV-1-infected individuals using an in-house method for identifying DRMs by genotyping. The overall prevalence of transmitted drug resistance (TDR) was found to be 11.3% (6/53), which is categorized as moderate level (5.0%-15.0%) of TDR according to the World Health Organization (WHO) survey guidelines. Surveillance drug resistance mutations to non-nucleoside reverse transcriptase inhibitors (NNRTI) were observed in 8.3% (n = 4) of the 48 RT sequences analyzed. No major DRMs related to the protease and nucleoside reverse transcriptase inhibitor (NRTIs) class of drugs were identified.

Mapping of Neutralizing Antibody Epitopes on the Envelope of Viruses Obtained from Plasma Samples Exhibiting Broad Cross-Clade Neutralization Potential Against HIV-1.

Several broadly neutralizing antibodies (bNAbs) that can target HIV strains with large degrees of variability have recently been identified. However, efforts to induce synthesis of such bNAbs that can protect against HIV infection have not met with much success. Identification of specific epitopes encoded in the HIV-1 envelope (Env) that can direct the host to synthesize bNAbs remains a challenge. In a previous study, we identified 12 antiretroviral therapy-naive HIV-1-infected individuals whose plasma exhibited broad cross-clade neutralization property against different clades of HIV-1. In this study, we sequenced the full-length HIV-1 gp160 from 11 of these individuals and analyzed the sequences to identify bNAb epitopes. We identified critical residues in the viral envelopes that contribute to the formation of conformational epitopes and possibly induce the production of bNAbs, using in silico methods. We found that many of the sequences had conserved glycans at positions N160 (10/11) and N332 (9/11), which are known to be critical for the binding of PG9/PG16-like and PGT128-like bNAbs, respectively. We also observed conservation of critical glycans at positions N234 and N276 critical for the interaction with CD4 binding site bNAbs in 8/11 and 11/11 sequences, respectively. We modeled the three-dimensional structure of the 11 HIV-1 envelopes and found that though each had structural differences, the critical residues were mostly present on the surface of the Env structures. The identified critical residues are proposed as candidates for further evaluation as bNAb epitopes.

Induction of circulating T follicular helper cells and regulatory T cells correlating with HIV-1 gp120 variable loop antibodies by a subtype C prophylactic vaccine tested in a Phase I trial in India.

A Phase I HIV-1 vaccine trial sponsored by the International AIDS Vaccine Initiative (IAVI) was conducted in India in 2009 to test a subtype C prophylactic vaccine in a prime-boost regimen comprising of a DNA prime (ADVAX) and MVA (TBC-M4) boost. The trial demonstrated that the regimen was safe and well tolerated and resulted in enhancement of HIV-specific immune responses. Preliminary observations on vaccine-induced immune responses were limited to analysis of neutralizing antibodies and IFN-γ ELISPOT response. The present study involves a more detailed analysis of the nature of the vaccine-induced humoral immune response using specimens that were archived from the volunteers at the time of the trial. Interestingly, we found vaccine induced production of V1/V2 and V3 region-specific antibodies in a significant proportion of vaccinees. Variable region antibody levels correlated directly with the frequency of circulating T follicular helper cells (Tfh) and regulatory T cells (Treg). Our findings provide encouraging evidence to demonstrate the immunogenicity of the tested vaccine. Better insights into vaccine-induced immune responses can aid in informing future design of a successfulHIV-1 vaccine.

Molecular Characteristics of the Envelope of Vertically Transmitted HIV-1 Strains from Infants with HIV Infection.

Mother-to-child transmission (MTCT) of HIV offers a good opportunity to study the dynamics of early viral evolution in the host environment to which the virus has partially adapted. Such studies would throw light on the unique features of the infecting viruses, which will subsequently help to design preventive or therapeutic measures against the newly infecting and evolving strains of HIV. Therefore, we undertook a study to determine the genetic divergence of proviral envelope sequences from the HIV-infected infants (<2 years). Detailed analysis revealed unique features of potential N-linked glycosylation sites (PNGS) and their frequency of occurrence that built on the difference in length of the V1V2 region of the envelope sequences. Surprisingly, frequency of PNGS in the V5 region was found to revert rapidly, in about 75% of the sequences, which could surmise a fitness disadvantage in the variant forms. Further, a stable net charge was observed in the V2 and V3 regions prompting us to speculate on the established interaction of the transmitted variant with the integrin α4ß7 receptor and R5 co-receptor, respectively. In brief, our observations suggest that differences in the length of the variable regions and variation in the frequency of PNGS in the envelope of the viruses obtained from very recently infected individuals in our population could be important characteristics of the unique quasispecies that is responsible for the spread of HIV in the early stages of infection in MTCT.

Expression and immunological characterization of cardamom mosaic virus coat protein displaying HIV gp41 epitopes.

The coat protein of cardamom mosaic virus (CdMV), a member of the genus Macluravirus, assembles into virus-like particles when expressed in an Escherichia coli expression system. The N and C-termini of the coat protein were engineered with the Kennedy peptide and the 2F5 and 4E10 epitopes of gp41 of HIV. The chimeric proteins reacted with sera from HIV positive persons and also stimulated secretion of cytokines by peripheral blood mononuclear cells from these persons. Thus, a system based on the coat protein of CdMV can be used to display HIV-1 antigens.