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Updated: Nov 9, 2025
Influenza A Virus Studies in a Mouse Model of Infection
Published on: September 7, 2017
Pathogenesis of murine astrovirus in experimentally infected mice
Hanako Morita1, Masahiko Yasuda2, Masafumi Yamamoto1
1ICLAS Monitoring Center, Central Institute for Experimental Animals, 3-25-12 Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-0821, Japan.
Abstract:
Astroviruses are often associated with gastrointestinal diseases in mammals and birds. Murine astrovirus (MuAstV) is frequently detected in laboratory mice. Previous studies on MuAstV in mice did not report any symptoms or lesions. However, little information is available regarding its pathogenicity in immunodeficient mice. Therefore, in this study, we experimentally infected germ-free NOD.Cg-PrkdcscidIl2rgtm1Sug/ShiJic (NOG) mice, which are severely immunodeficient, with MuAstV. Germ-free mice were used for experimental infection to eliminate the effects of intestinal bacteria. Mice in each group were then necropsied and subjected to PCR for MuAstV detection, MuAstV RNA quantification in each organ, and histopathological examination at 4 and 28 days post inoculation (DPI). Tissue samples from the small intestine were examined by transmission electron microscopy. No symptoms or abnormalities were detected in any mice during necropsy. The MuAstV concentration was highest in the lower small intestine, where it increased approximately 8-fold from 4 to 28 DPI. Transmission electron microscopy revealed circular virus particles of approximately 25 nm in diameter in the cytoplasm of the villous epithelial cells of the lower small intestine. Histopathological examination did not reveal any abnormalities, such as atrophy, in the intestinal villi. Our results suggest that MuAstV proliferates in the villous epithelial cells of the lower small intestine and has weak pathogenicity.
Insights
Murine astrovirus (MuAstV) replicates in the lower small intestine of immunodeficient mice. Despite viral proliferation, MuAstV shows weak pathogenicity, with no observed symptoms or intestinal damage.
Area of Science:
- Virology
- Immunology
- Gastroenterology
Background:
- Astroviruses commonly cause gastrointestinal illness in various species.
- Murine astrovirus (MuAstV) is prevalent in laboratory mice, but its pathogenicity, especially in immunodeficient models, remains poorly understood.
Purpose of the Study:
- To investigate the pathogenicity and replication of MuAstV in severely immunodeficient germ-free mice.
- To determine the effects of MuAstV infection on the intestinal tract of NOG mice.
Main Methods:
- Experimental infection of germ-free NOG mice with MuAstV.
- MuAstV detection and RNA quantification via PCR in various organs.
- Histopathological examination and transmission electron microscopy of intestinal tissues at 4 and 28 days post-inoculation.
Main Results:
- MuAstV replicated significantly in the lower small intestine, with an 8-fold increase in viral RNA concentration from 4 to 28 days post-inoculation.
- Transmission electron microscopy confirmed the presence of ~25 nm MuAstV particles within the cytoplasm of villous epithelial cells.
- No clinical symptoms, gross abnormalities, or histopathological changes, such as villous atrophy, were observed in infected mice.
Conclusions:
- MuAstV actively proliferates in the villous epithelial cells of the lower small intestine in immunodeficient mice.
- The study indicates that MuAstV possesses weak pathogenicity, as evidenced by the lack of observable disease manifestations or tissue damage.
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