13 ASTROVIRUS ALTERS THE GUT MUCUS BARRIER AND REDUCES COLONIZATION TO ENTEROPATHOGENIC E. COLI

Abstract

Abstract Goblet cells, specialized epithelial cells that produce mucus, are essential for gut health. Dysfunctional goblet cell secretion can weaken the mucus barrier, bringing commensal microbes and other lumenal contents in contact with the epithelial barrier, triggering inflammation. We recently discovered that murine astroviruses infect goblet cells in the small intestine, making it the first enteric virus in which this tropism has been recognized in vivo. To first determine whether astrovirus infection alters mucus production in goblet cells, we used periodic acid-Schiff staining of small intestinal tissues and found a thicker mucus layer in infected compared to mock-infected animals (1.85 to 2.51-fold, p<0.001). Because changes to the mucus barrier can alter the microbial environment in the gut, we used 16S metagenomic to characterize the microbiome after infection. We found that the relative frequency of well-characterized mucus-degrading bacteria significantly increased after infection (p<0.001). Using phylogenetic edge principal components analysis, we also identified distinct microbiome shifts between 0 and 14 days post-infection, corresponding to peak infection. Finally, to determine the extent to which these changes in the mucus barrier could have a functional consequence to host disease susceptibility, we developed a neonatal model for astrovirus and tested whether animals inoculated with enteropathogenic E. coli (EPEC), an adherent bacterial pathogen, would be protected from colonization. In comparison to animals inoculated with EPEC alone, co-infected animals had significantly reduced EPEC colonization (p<0.01). Together, these studies reveal a new avenue of enteric virus regulation of gut homeostasis and immunity via goblet cells and highlight astroviruses as a novel model to study the mucus barrier. Future studies are needed to determine whether astrovirus-induced increases in the mucus barrier protect from other gastrointestinal diseases and how these data translate to human astroviruses, which predominately infect children <1-year-old and coincides with the development of gut immunity.