Human gut virome and COVID-19: Modulating the extent of infection

Coronavirus disease 2019 (COVID-19) caused by the enveloped RNA virus SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2) primarily infects human lungs and then gut where active viral replication has been reported. The human gut also harbors different communities of commensal viruses (collectively known as the gut-virome (GV)) that play significant role in regulating host immunity. A gut-dysbiosis signature is observed with increased opportunistic pathogens and massive viral shifts in COVID-19 patients. The intensive two-way dialogues between lungs and gut involving the biome and immune cells of the both compartments are majorly responsible for massive systemic inflammation and immunity breakdown during a lung infection. Thence, during SARS-CoV-2 disease, the host GV might respond to the viral infection and subsequently influence disease progression as well as treatment outcome with additional manifestations. This chapter aims to explain the role of GV in altered homeostasis associated with disease severity and recovery processes based on existing records. Since evidence on direct linkage between human GV and SARS-CoV-2 infection is yet to be explored, understanding intestinal virome perturbation that underlies worse COVID-19 outcomes and severity is an unmet necessity.