Lack of Effect of Murine Astrovirus Infection on Dextran Sulfate–induced Colitis in NLRP3-deficient Mice

Murine astrovirus (MuAstV) is a recently identified, widespread infection among laboratory mice. MuAstV is found predominantly in the gastrointestinal tract of mice. Human and turkey astroviruses have been shown to disrupt tight junctions in the intestinal epithelium. The potential of MuAstV to alter research results was tested in a well-established dextran sodium sulfate (DSS)-induced colitis model in Nod-like receptor 3 (NLRP3)-deficient mice. This model offers a direct approach to determine whether MuAstV, as a component of the mouse microbiome, contributes to the issue of poor reproducibility in murine inflammatory bowel disease research. In this model, defective inflammasome activation causes loss of epithelial integrity, resulting in leakage of intestinal bacteria and colitis. Our goal was to determine whether MuAstV, which also may affect intestinal permeability, altered the onset or severity of colitis. Male and female mice (age, 8 to 12 wk) homozygous or heterozygous for an NLRP3 mutation were inoculated orally with MuAstV or mock-inoculated with media 3 or 20 d prior to being exposed to 2% DSS in their drinking water for 9 d. MuAstV infection alone did not cause clinical signs or histopathologic changes in NLRP3^–/– or NLRP3^+/– mice. No significant difference was seen in weight loss, clinical disease, intestinal inflammation, edema, hyperplasia, or mucosal ulceration between MuAstV- infected and mock-infected mice that received 2% DSS for 9 d. Therefore, MuAstV does not appear to be a confounding variable in the DSS colitis model in NLRP3 mice.