Functional profiling of COVID-19 respiratory tract microbiomes

In response to the ongoing global pandemic, progress has been made in understanding the molecular-level host interactions of the new coronavirus SARS-CoV-2 responsible for COVID-19. However, when the virus enters the body it interacts not only with the host but also with the micro-organisms already inhabiting the host. Understanding the virus-host-microbiome interactions can yield additional insights into the biological processes perturbed by viral invasion. With this aim we carry out a functional analysis of previously published RNA sequencing data of bronchoalveolar lavage fluid from eight COVID-19 patients, twenty-five community-acquired pneumonia patients, and twenty healthy controls. The resulting microbiome functional profiles and their top differentiating features clearly separate the cohorts. By examining the functional features in connection with their associated metabolic pathways, differentially abundant pathways are indicated, compared to both the community-acquired pneumonia and healthy cohorts. From this analysis, distinguishing signatures in COVID-19 respiratory tract microbiomes are identified, including decreased lipid and glycan metabolism pathways, and increased carbohydrate metabolism pathways. Here we present a framework for comparative functional analysis of microbiomes, the results from which can lead to new hypotheses on the host-microbiome interactions in healthy versus afflicted cohorts. The findings from this analysis call for further research on microbial functions and host-microbiome interactions during SARS-CoV-2 infection.