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Updated: Jan 28, 2026
Plaque Assay for Murine Norovirus
Published on: August 22, 2012
Seroconversion of 1-year-old Mice to Murine Norovirus
Julia Zaias1, Catia Farrington2, Robert S Livingston3
1Veterinary Resources, University of Miami, Miami, Florida, USA; Comparative Pathology, Department of Pathology and Laboratory Medicine, University of Miami, Miami, Florida, USA. Jzaias@med.miami.edu.
Abstract:
Rodent sentinel screening for adventitious pathogens is an integral part of many biomedical research institutes and universities that use rodents in research. Typical screening programs involving live sentinel animals typically purchase young SPF sentinel animals that are sampled and replaced quarterly. Previous reports suggest that mice as old as 6 mo are effective sentinels for various agents. In efforts to reduce the number of animals used in our sentinel program, we wanted to investigate the possibility of keeping sentinel animals inhouse for 12 mo at a time. We exposed mice (age, 40 to 48 wk) to murine norovirus (MNV) to test whether they could reliably produce detectable levels of antibodies (similar to younger mice) to this adventitious pathogen. Mice first exposed to MNV at 40 to 48 wk of age seroconverted to MNV after both direct inoculation (through gavage) and indirect exposure (from soiled-bedding transfer) at the same or greater frequency than mice first exposed at 8 to 12 wk of age. These findings indicate that, at least for MNV, sentinel residence time can be extended from 3 to 12 mo without compromising the reliability of seroconversion, thus ultimately reducing sentinel animal numbers. This practice, combined with nonanimal testing modalities (for example, exhaust duct sampling), can increase the sensitivity and specificity of rodent surveillance programs and minimize the use of live animals.
Insights
Extending sentinel rodent residence time to 12 months, even for older mice exposed to murine norovirus (MNV), maintains reliable antibody detection. This approach reduces animal use in research surveillance programs.
Area of Science:
- Veterinary Pathology
- Animal Health Monitoring
- Biomedical Research Support
Background:
- Rodent sentinel screening is crucial for detecting adventitious pathogens in research settings.
- Current programs typically use young sentinel animals replaced quarterly, leading to significant animal numbers.
- Previous studies indicated older mice (up to 6 months) can serve as effective sentinels.
Purpose of the Study:
- To investigate extending sentinel animal housing time from 3 to 12 months.
- To assess if older mice (40-48 weeks) can reliably seroconvert to murine norovirus (MNV).
- To reduce the overall number of animals used in sentinel surveillance programs.
Main Methods:
- Adult mice (40-48 weeks old) were exposed to MNV via direct inoculation (gavage) or indirect exposure (soiled bedding).
- Antibody production (seroconversion) to MNV was measured in exposed older mice.
- Seroconversion rates in older mice were compared to those of younger mice (8-12 weeks).
Main Results:
- Mice exposed to MNV at 40-48 weeks of age demonstrated seroconversion.
- Seroconversion frequency in older mice was comparable to or greater than that observed in younger mice.
- Extended sentinel residence time (12 months) did not compromise seroconversion reliability for MNV.
Conclusions:
- Sentinel residence time for MNV surveillance can be extended to 12 months without loss of reliability.
- This extension significantly reduces the number of sentinel animals required.
- Combining extended residence with non-animal methods enhances surveillance sensitivity and specificity while minimizing animal use.
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