Long-read 16S-seq reveals nasopharynx microbial dysbiosis and enrichment of Mycobacterium and Mycoplasma in COVID-19 patients: a potential source of co-infection.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major global health concern. This virus infects the upper respiratory tract and causes pneumonia-like symptoms. So far, few studies have shown alterations in nasopharyngeal (NP) microbial diversity, enrichment of opportunistic pathogens and their role in co-infections during respiratory infections. Therefore, we hypothesized that microbial diversity changes, with increase in the population of opportunistic pathogens, during SARS-CoV2 infection in the nasopharynx, which may be involved in co-infection in COVID-19 patients. The 16S rRNA variable regions, V1-V9, of NP samples of control and COVID-19 (symptomatic and asymptomatic) patients were sequenced using the Oxford Nanopore™ technology. Comprehensive bioinformatics analysis for determining alpha/beta diversities, non-metric multidimensional scaling, correlation studies, canonical correspondence analysis, linear discriminate analysis, and dysbiosis index were used to analyze the control and COVID-19-specific NP microbiomes. We observed significant dysbiosis in the COVID-19 NP microbiome with an increase in the abundance of opportunistic pathogens at genus and species levels in asymptomatic/symptomatic patients. The significant abundance of Mycobacteria spp. and Mycoplasma spp. in symptomatic patients suggests their association and role in co-infections in COVID-19 patients. Furthermore, we found strong correlation of enrichment of Mycobacteria and Mycoplasma with the occurrences of chest pain and fever in symptomatic COVID-19 patients. This is the first study from India to show the abundance of Mycobacteria and Mycoplasma opportunistic pathogens in non-hospitalized COVID-19 patients and their relationship with symptoms, indicating the possibility of co-infections.

Analysis of Indian SARS-CoV-2 Genomes Reveals Prevalence of D614G Mutation in Spike Protein Predicting an Increase in Interaction With TMPRSS2 and Virus Infectivity.

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, has emerged as a global pandemic worldwide. In this study, we used ARTIC primers-based amplicon sequencing to profile 225 SARS-CoV-2 genomes from India. Phylogenetic analysis of 202 high-quality assemblies identified the presence of all the five reported clades 19A, 19B, 20A, 20B, and 20C in the population. The analyses revealed Europe and Southeast Asia as two major routes for introduction of the disease in India followed by local transmission. Interestingly, the19B clade was found to be more prevalent in our sequenced genomes (17%) compared to other genomes reported so far from India. Haplotype network analysis showed evolution of 19A and 19B clades in parallel from predominantly Gujarat state in India, suggesting it to be one of the major routes of disease transmission in India during the months of March and April, whereas 20B and 20C appeared to evolve from 20A. At the same time, 20A and 20B clades depicted prevalence of four common mutations 241 C > T in 5' UTR, P4715L, F942F along with D614G in the Spike protein. D614G mutation has been reported to increase virus shedding and infectivity. Our molecular modeling and docking analysis identified that D614G mutation resulted in enhanced affinity of Spike S1-S2 hinge region with TMPRSS2 protease, possibly the reason for increased shedding of S1 domain in G614 as compared to D614. Moreover, we also observed an increased concordance of G614 mutation with the viral load, as evident from decreased Ct value of Spike and the ORF1ab gene.