Murine Astrovirus Infection and Transmission in Neonatal CD1 Mice

Area of Science:

• Veterinary Virology
• Laboratory Animal Science
• Infectious Disease Epidemiology

Background:

• Murine astrovirus (MuAstV) is an emerging pathogen in research settings.
• Understanding MuAstV transmission dynamics is crucial for maintaining disease-free laboratory animal colonies.

Purpose of the Study:

• To investigate the duration of MuAstV shedding in dams and pups.
• To assess the susceptibility of different age groups to infection.
• To evaluate the effectiveness of soiled-bedding sentinels and environmental monitoring for MuAstV detection.

Main Methods:

• Oral inoculation of CD1 dams and their litters (3-day-old and 13-day-old pups) with MuAstV.
• Collection and analysis of fecal, intestinal, and organ samples for MuAstV RNA.
• Environmental sampling using cage swabs and ventilated rack exhaust manifolds.
• Sentinel mouse exposure to soiled bedding from infected animals.

Main Results:

• MuAstV RNA was detected in dams up to postnatal day (PND) 42, with highest viral loads in the intestines.
• Pups born to infected dams showed high rates of fecal shedding (97%) from 3 to 9 weeks of age.
• Environmental swabs and soiled-bedding sentinels demonstrated high detection rates, even with stored bedding.
• No significant clinical signs or effects on pup weight gain were observed.

Conclusions:

• MuAstV establishes persistent infections in mice with prolonged shedding periods.
• Soiled-bedding sentinels and environmental monitoring are highly effective for detecting MuAstV in laboratory settings.
• Early-life MuAstV infection does not appear to cause overt disease but can lead to widespread shedding.