Antimicrobial resistance and virulence in Helicobacter pylori: Genomic insights.

Microbes evolve rapidly by modifying their genome through mutations or acquisition of genetic elements. Antimicrobial resistance in Helicobacter pylori is increasingly prevalent in India. However, limited information is available about the genome of resistant H. pylori isolated from India. Our pan- and core-genome based analyses of 54 Indian H. pylori strains revealed plasticity of its genome. H. pylori is highly heterogenous both in terms of the genomic content and DNA sequence homology of ARGs and virulence factors. We observed that the H. pylori strains are clustered according to their geographical locations. The presence of point mutations in the ARGs and absence of acquired genetic elements linked with ARGs suggest target modifications are the primary mechanism of its antibiotic resistance. The findings of the present study would help in better understanding the emergence of drug-resistant H. pylori and controlling gastric disorders by advancing clinical guidance on selected treatment regimens.

Vaginal Microbiome of Pregnant Indian Women: Insights into the Genome of Dominant Lactobacillus Species.

The trillions of microorganisms residing in the human body display varying degrees of compositional and functional diversities within and between individuals and contribute significantly to host physiology and susceptibility to disease. Microbial species present in the vaginal milieu of reproductive age women showed a large personal component and varies widely in different ethnic groups at the taxonomic, genomic, and functional levels. Lactobacillus iners, L. crispatus, L. gasseri, L. jensenii, and L. johnsonii are most frequently detected bacterial species in the vaginal milieu of reproductive age women. However, we currently lack (i) an understanding of the baseline vaginal microbiota of reproductive age Indian women, (ii) the extent of taxonomic and functional variations of vaginal microbiota between individuals and (iii) the genomic repertoires of the dominant vaginal microbiota associated with the Indian subjects. In our study, we analyzed the metagenome of high vaginal swab (HVS) samples collected from 40 pregnant Indian women enrolled in the GARBH-Ini cohort. Composition and abundance of bacterial species was characterized by pyrosequencing 16S rRNA gene. We identified 3067 OTUs with ≥ 10 reads from four different bacterial phyla. Several species of lactobacilli were clustered into three community state types (CSTs). L. iners, L. crispatus, L. gasseri, and L. jensenii are the most frequently detected Lactobacillus species in the vaginal environment of Indian women. Other than Lactobacillus, several species of Halomonas were also identified in the vaginal environment of most of the women sampled. To gain genomic and functional insights, we isolated several Lactobacillus species from the HVS samples and explored their whole genome sequences by shotgun sequencing. We analyzed the genome of dominant Lactobacillus species, L. iners, L. crispatus, L. gasseri, and L. paragesseri to represent the CSTs and identify functions that may influence the composition of complex vaginal microbial ecology. This study reports for the first time the vaginal microbial ecology of Indian women and genomic insights into L. iners, L. crispatus, L. gasseri, and L. paragesseri commonly found in the genital tract of reproductive age women.

Comparative analysis of SARS-CoV-2 envelope viroporin mutations from COVID-19 deceased and surviving patients revealed implications on its ion-channel activities and correlation with patient mortality.

One major obstacle in designing a successful therapeutic regimen to combat COVID-19 pandemic is the frequent occurrence of mutations in the SARS-CoV-2 resulting in patient to patient variations. Out of the four structural proteins of SARS-CoV-2 namely, spike, envelope, nucleocapsid and membrane, envelope protein governs the virus pathogenicity and induction of acute-respiratory-distress-syndrome which is the major cause of death in COVID-19 patients. These effects are facilitated by the viroporin (ion-channel) like activities of the envelope protein. Our current work reports metagenomic analysis of envelope protein at the amino acid sequence level through mining all the available SARS-CoV-2 genomes from the GISAID and coronapp servers. We found majority of mutations in envelope protein were localized at or near PDZ binding motif. Our analysis also demonstrates that the acquired mutations might have important implications on its structure and ion-channel activity. A statistical correlation between specific mutations (e.g. F4F, R69I, P71L, L73F) with patient mortalities were also observed, based on the patient data available for 18,691 SARS-CoV-2-genomes in the GISAID database till 30 April 2021. Albeit, whether these mutations exist as the cause or the effect of co-infections and/or co-morbid disorders within COVID-19 patients is still unclear. Moreover, most of the current vaccine and therapeutic interventions are revolving around spike protein. However, emphasizing on envelope protein's (1) conserved epitopes, (2) pathogenicity attenuating mutations, and (3) mutations present in the deceased patients, as reported in our present study, new directions to the ongoing efforts of therapeutic developments against COVID-19 can be achieved by targeting envelope viroporin.

The Vaginal Microbial Signatures of Preterm Birth Delivery in Indian Women.

Background: The incidence of preterm birth (PTB) in India is around 13%. Specific bacterial communities or individual taxon living in the vaginal milieu of pregnant women is a potential risk factor for PTB and may play an important role in its pathophysiology. Besides, bacterial taxa associated with PTB vary across populations. Objective: Conduct a comparative analysis of vaginal microbiome composition and microbial genomic repertoires of women who enrolled in the Interdisciplinary Group for Advanced Research on Birth Outcomes - A DBT India Initiative (GARBH-Ini) pregnancy cohort to identify bacterial taxa associated with term birth (TB) and PTB in Indian women. Methods: Vaginal swabs were collected during all three trimesters from 38 pregnant Indian women who delivered spontaneous term (n=20) and preterm (n=18) neonates. Paired-end sequencing of V3-V4 region of 16S rRNA gene was performed using the metagenomic DNA isolated from vaginal swabs (n=115). Whole genome sequencing of bacterial species associated with birth outcomes was carried out by shotgun method. Lactobacillus species were grown anaerobically in the De Man, Rogosa and Sharpe (MRS) agar culture medium for isolation of genomic DNA and whole genome sequencing. Results: Vaginal microbiome of both term and preterm samples reveals similar alpha diversity indices. However, significantly higher abundance of Lactobacillus iners (p-value All_Trimesters<0.02), Megasphaera sp (p-value1st_Trimester <0.05), Gardnerella vaginalis (p-value2nd_Trimester= 0.01) and Sneathia sanguinegens (p-value2nd_Trimester <0.0001) were identified in preterm samples whereas higher abundance of L. gasseri (p-value3rd_Trimester =0.010) was observed in term samples by Wilcoxon rank-sum test. The relative abundance of L. iners, and Megasphaera sp. were found to be significantly different over time between term and preterm mothers. Analyses of the representative genomes of L. crispatus and L. gasseri indicate presence of secretory transcriptional regulator and several ribosomally synthesized antimicrobial peptides correlated with anti-inflammatory condition in the vagina. These findings indicate protective role of L. crispatus and L. gasseri in reducing the risk of PTB. Conclusion: Our findings indicate that the dominance of specific Lactobacillus species and few other facultative anaerobes are associated with birth outcomes.

Rational targeting of Wzb phosphatase and Wzc kinase interaction inhibits extracellular polysaccharides synthesis and biofilm formation in Acinetobacter baumannii.

Acinetobacter baumannii is an opportunistic nosocomial pathogen, and responsible for high mortality and morbidity. Biofilm formation is one of the resistance determinants, where extracellular polysaccharide (EPS) is an essential component. EPS synthesis and its export is regulated by the bacterial Wza-Wzb-Wzc system. Wzc exhibits auto-phosphorylation protein tyrosine kinase activity, while Wzb is a protein tyrosine phosphatase. Wzb mediates dephosphorylation of Wzc. Dephosphorylated Wzc is required for the export of the EPS through porin Wza-Wzc complex. It shows that the interaction of Wzb with Wzc is critical for the export of EPS. Therefore, if the Wzb-Wzc interaction is inhibited, then it might hinder the EPS transport and diminish the biofilm formation. In this study, we have modelled the Wzb, and Wzc proteins and further validated using PSVS, ProSA, RAMPAGE, and PDBsum. The modelled proteins were used for protein-protein docking. The docked protein-protein complex was minimized by Schrodinger software using OPLS_2005 force field. The binding site of the minimized Wzb-Wzc complex was identified by Sitemap. The high throughput virtual screening identified Labetalol hydrochloride and 4-{1-hydroxy-2-[(1-methyl-3-phenylpropyl) amino] propyl} phenol from FDA-approved drug library based on their interaction at the interface of Wzb-Wzc complex. The inhibitor-protein complex was further undergone molecular mechanics analysis using Generalized Born model and Solvent Accessibility (MMGBSA) to estimate the binding free energies. The lead was also used to generate the pharmacophore model and screening the molecule with antimicrobial scaffold. The identified lead was experimentally validated for its effect on EPS quantity and biofilm formation by A. baumannii. Wzb-Wzc interaction is essential for biofilm and EPS export; hence, the identified lead might be useful to regulate the biofilm formation by A. baumannii.

Insights into the gastrointestinal tract microbiomes of Indian population.

Trillions of microbes living in the gastrointestinal tract (GIT) of the human body finely tune homeostatic equilibrium in the GIT ecosystem and encode key functionalities that play crucial role in host metabolic functions, synthesis of macro- and micronutrients, xenobiotics metabolisms, development of innate and adaptive immune systems, tissue and organ developments and resistance against invasion of enteric pathogens. The microbial diversity and richness of GIT ecosystem varies greatly between individuals and over time. Extent of taxonomic and functional variations in GIT ecosystem is linked with dietary habit, pharmaceuticals usages, age, sex, body mass index, ethnicity, geography, altitude and civilization. Understanding a holistic picture of GIT microbiome of healthy people living across geography and identifying population specific 'keystone' taxa is of immense importance for identifying microbial species that may provide protection against chronic and metabolic diseases. Knowledge on geographic or ethnicity specific microbial signatures may also help us to understand the varied efficacy of different drugs and vaccines in different population. India is the home of more than 1.36 billion people belonging to 2000 human communities residing in well distinct geography. In the present review, we discuss the microbial signatures in health and diseases of the rural and urban Indians living in sea level and high altitude areas.