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The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has adversely affected humankind and caused millions of deaths globally since January 2020. Robust and quick serological tests such as antibody detection assays for SARS-CoV-2 provide relevant information and aid in the process of vaccine development and diagnostics, as well as in sero-epidemiological monitoring of antibody response to the virus. The receptor-binding domain (RBD) of spike and nucleocapsid protein are specific targets for detecting SARS-CoV-2 antibodies. Here, we present the development of a stable spike (S) and nucleocapsid (N) protein-based ELISA antibody detection test "CoroSuchak," with 99% sensitivity, 98% specificity, cost-effective, and detection in a minimum time for serodiagnosis and mass screening of the population for antibodies against SARS-CoV-2. Blood samples were analyzed from 374 SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) positive, 772 negative and asymptomatic, and 874 random groups of subjects. We found that the antibody titer was significantly higher (p 0.0001) in infected and vaccinated group compared to the only vaccinated and only infected group. Using enzyme-linked immunosorbent assay (ELISA), we detected SARS-CoV-2 immunoglobulin G (IgG) antibodies in 118/123 (96%) infected individuals, 570/653 (87%) non-infected but vaccinated individuals, 231/237 (97%) individuals who were both infected and vaccinated, and 499/874 (57%) from randomly selected individuals from the first and second waves of the pandemic. Similarly in the third wave, 14/14 (100%) infected and 16/20 (80%) RT-PCR-negative but symptomatic subjects were detected. Thus, the highly sensitive and specific in-house developed ELISA antibody detection kit "CoroSuchak" is extremely useful to determine the seroprevalence of SARS-CoV-2 antibodies in the coronavirus-exposed population. KEY POINTS: •Indigenous kit using a combination of spike and nucleocapsid proteins and peptide sequences. •High sensitivity and specificity to detect variants. •Highly sensitive for mass screening.

Human microbial alterations are associated with environmental stress, nutrition, genetic, and triggering de-novo variations. Nevertheless, the human gut microbiome at extreme altitude (> 5800 m) remains unexplored. We aimed to demonstrate the microbial predominance in individuals with the same ethnicity and dietary pattern at extreme altitude with unique challenges like cold, hypoxia, radiation, etc. Different analysis pipelines were used for fecal whole genome sequencing at 210 m, 3500 m, 4420 m and 5805 m, and 16S rRNA V3-V4 regions amplification sequencing of 19 individuals belonging to the same ethnicity and dietary pattern for the presence of taxonomy and functional potential and confirming the prediction up to the strain level within the same cohort. Principal component analysis revealed distinct microbiome changes at different altitudes, with varied and higher Bacteroides and Prevotella ratio. There was a predominance of genus Prevotella at altitudes 4420 m and 5805 m than at 210 m and 3500 m. The appearance of species Prevotella copri strain 61,740 increased significantly at extreme altitude, whereas co-occurrence of other bacterial strains had a different pattern than Prevotella. The extensive strain-level analysis indicated alteration in the metabolic pathways. This study under the stressful and hypoxic environment of extreme altitudes, associated microbial variation with altered metabolic pathways, reveals the influence of extreme environment on human gut microbiota with the predominance of Prevotella.

Mucosal immunity of Indian Antarctic personnel was analysed during the 34th Indian Scientific Expedition to Antarctica (ISEA) by ship voyage. Serum and salivary IgA, IgA1 and IgA2 levels along with salivary cortisol and TGF-β were quantified by enzyme-linked immunosorbent assay. Samples were collected at three different time points (T1, T2 and T3) during the expedition. Serum and salivary IgA, IgA1 and IgA2 concentrations incrementally increased towards the end of the expedition as compared to the beginning of the expedition. Salivary IgA and TGF-β levels were significantly altered during the expedition. Levels of IgA1 (P = 0.0007) and IgA2 (P = 0.0135) increased significantly at T3 as compared to T1. Additionally, significant changes in serum IgA were observed, with peak levels at T3 (P = 0.0015) and T2 (P < 0.001). However, the level of serum IgA2 was also significantly altered at T3 (P < 0.05) and T2 (P = 0.0006) in comparison with T1. The exact cause of the changes in serum and salivary IgA, IgA1, IgA2 and TGF-β levels during the summer expedition are unknown; however, the changes are evident in mucosal immunity.

Alterations in the gut immune axis under hypobaric hypoxia (HH) exposure may be a consequence of microbial dysbiosis. The mechanism of induction of gut inflammation by alterations in gut bacterial and viral populations has not been discovered meticulously. Here we used whole-genome and 16S rRNA sequencing to characterize the taxonomic and functional shifts in the faecal microbiome after HH exposure. Ten faecal samples from unexposed and HH exposed (3 days, 7 days and 14 days) Sprague–Dawley rats were analyzed. 16S rRNA sequencing was conducted on Illumina MiSeq platform using universal primers and analysed using QIIME (Greengenes database). WGS sequencing was done on Illumina HiSEQ 2500 platform and analysed using MOCAT2 (eggNOG database). HH exhibited an overarching effect on taxonomic and functional gene composition. A significant change in α-diversity at phylum level and β-diversity at phylum and genus level were observed between control and HH exposed groups. Significant (p

Outbreak of COVID-19 pandemic in December 2019 affected millions of people globally. After substantial research, there is no specific and reliable biomarker available till date. Present study was designed to identify specific biomarkers to predict COVID-19 severity and tool for formulating treatment. A small cohort of subjects (n=43) were enrolled and categorized in four study groups; Dead (n=16), Severe (n=10) and Moderate (n=7) patients and healthy controls (n=10). Small RNA sequencing was done on Illumina platform after isolation of microRNA from peripheral blood. Differential expression (DE) of miRNA (patients groups compared to control) revealed 118 down-regulated and 103 up-regulated known miRNAs with fold change (FC) expression ≥2 folds and p≤0.05. DE miRNAs were then subjected to functional enrichment and network analysis. Bioinformatic analysis resulted in 31 miRNAs (24 Down-regulated; 7 up-regulated) significantly associated with COVID-19 having AUC>0.8 obtained from ROC curve. Seventeen out of 31 DE miRNAs have been linked to COVID-19 in previous studies. Three miRNAs, hsa-miR-147b-5p and hsa-miR-107 (down-regulated) and hsa-miR-1299 (up-regulated) showed significant unique DE in Dead patients. Another set of 4 miRNAs, hsa-miR-224-5p (down-regulated) and hsa-miR-4659b-3p, hsa-miR-495-3p and hsa-miR-335-3p were differentially up-regulated uniquely in Severe patients. Members of three miRNA families, hsa-miR-20, hsa-miR-32 and hsa-miR-548 were significantly down-regulated in all patients group in comparison to healthy controls. Thus a distinct miRNA expression profile was observed in Dead, Severe and Moderate COVID-19 patients. Present study suggests a panel of miRNAs which identified in COVID-19 patients and could be utilized as potential diagnostic biomarkers for predicting COVID-19 severity.

Ship voyage to Antarctica is a stressful journey for expedition members. The response of human gut microbiota to ship voyage and a feasible approach to maintain gut health, is still unexplored. The present findings describe a 24-day long longitudinal study involving 19 members from 38th Indian Antarctic Expedition, to investigate the impact of ship voyage and effect of probiotic intervention on gut microbiota. Fecal samples collected on day 0 as baseline and at the end of ship voyage (day 24), were analyzed using whole genome shotgun sequencing. Probiotic intervention reduced the sea sickness by 10% compared to 44% in placebo group. The gut microbiome in placebo group members on day 0 and day 24, indicated significant alteration compared to a marginal change in the microbial composition in probiotic group. Functional analysis revealed significant alterations in carbohydrate and amino acid metabolism. Carbohydrate-active enzymes analysis represented functional genes involved in glycoside hydrolases, glycosyltransferases and carbohydrate binding modules, for maintaining gut microbiome homeostasis. Suggesting thereby the possible mechanism of probiotic in stabilizing and restoring gut microflora during stressful ship journey. The present study is first of its kind, providing a feasible approach for protecting gut health during Antarctic expedition involving ship voyage.

High altitude-induced gastrointestinal (GI) problems are potentially life-threatening. GI tract bleeding and inflammation are the major problems induced by hypobaric hypoxia (HH). In this study, effects of acute exposure to HH up to 14 days at 7620 m on GI immune function have been studied. To fulfill these objectives, Sprague-Dawley (SD) rats were divided into five groups namely Control and HH exposed (1, 3, 7, and 14 days). All groups except control were exposed to 7620 m of HH in an animal decompression chamber for the respective time intervals. Different degrees of intestinal mucosal damage in terms of increased mucosal permeability and disruption of intestinal villi were observed for different time intervals. HH exposure also upregulated secretory immunoglobulin A (sIgA) and proinflammatory cytokines in GI lavage along with proinflammatory markers such as toll-like receptor 4 (TLR4) and inducible nitric oxide synthase (iNOS). HH exposure of rats for 7 days significantly increased interleukin-17 (IL-17) and natural killer (NK) cell and dendritic cell populations compared with unexposed control rats. However, the number of naive T cells was significantly decreased in Peyer's patches. Our results connect HH to GI immune axis and highlight Th17 cells and proinflammatory molecules as potential therapeutic targets to counteract HH-induced GI dysfunction.

Human microbial alterations are associated with environmental stress, nutritional, genetic and triggering de-novo variations. Nevertheless, human gut microbiome at extreme altitude (>5800 m) remains unexplored. We aimed to demonstrate the microbial predominance in individuals with same ethnicity and dietary pattern at extreme altitude with unique challenges like cold, hypoxia, radiation etc. Different analysis pipelines were used for fecal whole genome sequencing at 210m, 3500m, 4420m and 5805m, and 16s rRNA V3-V4 regions amplification sequencing of 19 individuals belonging to the same ethnicity and dietary pattern, for presence of taxonomy & functional potential and confirming the prediction upto the strain level within the same cohort. Principal component analysis, revealed distinct microbiome changes at different altitudes, with varied and higher Bacteroides and Prevotella ratio. There was predominance of genus Prevotella at altitudes 4420m & 5805m than at 210m & 3500m. Appearance of species Prevotella copri strain 61740 was increasing significantly at extreme altitudes, whereas co-occurrence of other bacterial strains had different pattern than Prevotella. The extensive strain level analysis indicated alteration in the metabolic pathways. This study under stressful and hypoxic environment of extreme altitudes, associated microbial variation with altered metabolic pathways, reveals influence of extreme environment on human gut microbiota with predominance of Prevotella.