Murine astrovirus infection course and antibody response in different mouse strains

Monitoring the health of mice used in animal experiments constitutes an important instrument toward microbiological standardization, as infections can alter physiological parameters and immune reactions and may therefore have an essential impact on experimental outcome. In view of the high prevalence rates of murine astrovirus (MuAstV) infections in laboratory mouse facilities worldwide and the potential impact on research outcomes and reproducibility, there is a need to include MuAstV in the existing laboratory mice health monitoring programs. Here, to determine the sentinel strain and diagnostic method of choice, we aimed to assess the course of MuAstV infection and the resulting immune response in three immunocompetent mouse strains (Crl:CD1 (ICR), C57BL/6J and BALB/cOlaHsd) and one immunodeficient strain (NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ) by analyzing blood, feces and tissue samples with MuAstV-specific polymerase chain reaction and serology. Depending on the mouse strain, the duration of infection and viral load differed significantly, as well as the rapidity and quantity of antibody production. Virus shedding in immunocompetent mice was limited to a maximum of 4 weeks, whereas immunodeficient mice shed virus for the entire duration of this study. A fast antibody response with high titers was found only in outbred CD1 mice. In C57BL/6J and BALB/c mice, however, seropositivity and high antibody levels were reached only after the second infection. These results not only improve our understanding of the infection characteristics of MuAstV, presumably the most prevalent virus in laboratory mice, but also help to set up a health monitoring routine giving meaningful and reliable results on the MuAstV infection status of laboratory mouse populations.