Composition of nasopharyngeal microbiota in individuals with SARS-COV-2 infection across three COVID-19 waves in India (preprint)

ABSTRACT

Background: SARS-COV-2 is an enveloped RNA virus that is responsible for the global pandemic COVID-19. The virus is reported to cause dysbiosis of the Human Nasopharyngeal microbiota, consequently regulating the host immunity and infection pathophysiology. The compositional change in microbial diversity due to the virus has been reported by independent authors in smaller cohorts and different geographical regions, with a few correlating with fungal and bacterial co-infections. Here, we study for the first time, the nasopharyngeal microbial diversity in the COVID-19 patients, across the three waves in India and explore its correlation with the causative virus variant (and/or the severity of symptoms, if any). Methods: We profiled the nasopharyngeal microbiota of 589 Indian subjects, across the three waves (First; n=181, Second; n=217, Third; n=191), which were further categorized as COVID-19 positives and COVID-19 negatives. These respective groups were further divided into subgroups based on the symptoms as Asymptomatic and Symptomatic. The nasopharyngeal swabs were collected from subjects providing samples for diagnostics purposes at the Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India. Using high throughput 16S rRNA gene amplicon-based sequencing, we sequenced and profiled the nasopharyngeal DNA microbiome prior to subjecting them to diversity, composition and network analyses. Results: Patients infected with SARS-COV-2 showed a reduced microbial alpha diversity compared to the COVID-19 negatives, in a wave-dependent manner, as implicated by measuring the alpha diversity indices. Furthermore, the compositional change in the community was found to be significantly associated with the viral load as well as the severity of the symptoms observed in the patients. Preliminary taxonomic analysis indicated that, overall, Firmicutes, Proteobacteria, and Actinobacteriota were amongst the dominating Phyla, while Staphylococcaceae and Corynebacteriaceae were the most abundant Families. Also, the microbiota signatures of the first and third wave were more similar to each other at the phylum level compared to the second wave. However, the abundance of microbes varied greatly between the major groups i.e COVID-19 positives and the negatives at the family level, in the respective waves. A similar observation was made where both the commensals and pathobionts differed in abundance between the patient subgroups. Interestingly, the change in microbial network architecture from first to second wave was driven by opportunistic pathogens such as Paenibacillus, Peptostreptococcus, and Solobacterium while Leptotrichia and Actinomyces were noted to be taxonomic groups driving the changes during the third wave when compared to the second wave. Conclusion: In the Indian cohort examined, SARS-COV-2 infection perturbs the nasopharyngeal microbiome, resulting in lower & varied diversity in the niche, irrespective of the virus variant (& thus, the COVID wave) and the disease severity. Whether these changes assist in COVID-19 disease onset & progression, would be interesting to explore in the future.