Microbiota do not restrict rotavirus infection of colon.

Rotavirus is associated with extensive infection of the small intestine, whereas colon is considered to be uninfected. Considering that almost all bacteria in the gut colonize the colon, we hypothesized that the microbiota may act as a physical barrier preventing rotavirus infection in the colon in vivo . To address this hypothesis, we used human and mice colonoids, and biopsies of different intestinal segments of untreated and antibiotic-treated adult and infant mice. Rotavirus quantification was performed by qPCR and volumetric 3D imaging of intestinal segments. By 3D imaging, we observed infection in all the small intestinal segments, most extensively in the ileum, with most limited number of infected cells in colon. Broad-spectrum antibiotic treatment yielded no significant change in infection in either ileum or colon of adults and mice pups, although there is a substantial decrease in microbial load. We also show that rotavirus can successfully infect and replicate in colonoids from both mice and humans. Collectively, our data, including novel 3D imaging of the gut, mouse, and human colonoids, conclude that microbiota does not affect rotavirus infection in colon.IMPORTANCEAlterations of the gut microbiome can have significant effects on gastrointestinal homeostasis leading to various diseases and symptoms. Increased understanding of rotavirus infection in relation to the microbiota can provide better understanding on how microbiota can be used for clinical prevention as well as treatment strategies. Our volumetric 3D imaging data show that antibiotic treatment and its consequent reduction of the microbial load does not alter the extent of rotavirus infection of enterocytes in the small intestine and that restriction factors other than bacteria limit the infection of colonocytes.