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Updated: Jul 5, 2026
Plaque Assay for Murine Norovirus
Published on: August 22, 2012
Soiled-bedding sentinel detection of murine norovirus 4
Christopher A Manuel1, Charlie C Hsu, Lela K Riley
1Research Animal Diagnostic Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA. manuelc@missouri.edu
Abstract:
According to serologic surveys, murine norovirus (MNV) is the most prevalent viral pathogen infecting mice used in biomedical research. However, the use of sentinel mice to detect MNV-infected mouse populations has not been evaluated thoroughly. To this end, an experimental method of soiled bedding transfer was created to mimic a quarterly sentinel monitoring program. Soiled bedding (15 or 30 cm3) from ICR mice experimentally infected with MNV4 was transferred weekly to cages of pair-housed 4-wk-old ICR mice. After 12 wk, both mice in 80% (4 of 5) of cages receiving either 15 or 30 cm3 of soiled bedding were seropositive for MNV and were shedding virus in feces. To evaluate the stability of MNV RNA in mouse feces, fecal pellets from MNV-infected sentinel mice were stored at room temperature for as long as 14 d. After storage, all fecal samples tested positive for MNV by RT-PCR. To determine whether fecal samples could be pooled for MNV detection, 1 MNV-positive fecal pellet was combined with either 9 or 19 MNV-negative fecal pellets. All pooled fecal samples were positive for MNV by RT-PCR at both dilutions. These data indicate that although MNV-infected mouse populations can be detected by exposing sentinel mice to MNV-contaminated bedding, detection failures can occur. In addition, there was high agreement in the MNV infection status of cohoused sentinel mice. These data also demonstrate that MNV is readily detectable in pooled fecal samples and in mouse feces stored at room temperature for 2 wk.
Insights
Murine norovirus (MNV) can be detected in research mice using soiled bedding from infected animals. This method shows promise for monitoring MNV, but detection failures can occur.
Area of Science:
- Veterinary Virology
- Animal Models in Research
Background:
- Murine norovirus (MNV) is a common viral pathogen in laboratory mice.
- Current methods for detecting MNV in mouse populations require thorough evaluation.
Purpose of the Study:
- To evaluate the effectiveness of sentinel mice exposed to soiled bedding for detecting MNV infection.
- To assess the stability of MNV RNA in feces and the feasibility of pooling fecal samples for detection.
Main Methods:
- Experimental infection of sentinel mice with MNV via soiled bedding transfer.
- Storage of fecal samples at room temperature to assess RNA stability.
- RT-PCR analysis of individual and pooled fecal samples for MNV detection.
Main Results:
- Sentinel mice exposed to contaminated bedding became infected and shed MNV in 80% of cases.
- MNV RNA remained detectable in feces stored at room temperature for up to 14 days.
- Pooled fecal samples were reliably positive for MNV, even with up to 19 negative samples.
Conclusions:
- Sentinel mice exposed to soiled bedding can detect MNV infection, though failures are possible.
- MNV is stable in feces for extended periods and detectable in pooled samples, simplifying monitoring.
