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Updated: May 12, 2026
Swab Sampling Method for the Detection of Human Norovirus on Surfaces
Published on: February 6, 2017
Pitfalls in mouse norovirus (MNV) detection in fecal samples using RT-PCR, and construction of new MNV-specific
Masaru Tajima1, Yuko Kotani, Tsutomu Kurosawa
1The Institute of Experimental Animal Sciences, Faculty of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Abstract:
The murine norovirus (MNV), which belongs to the Caliciviridae family, is prevalent in laboratory mice. Since this virus affects macrophages and dendritic cells, infected mice are not suitable for immunological investigations, making it important to detect MNV infections accurately. When we tested RNA extracts derived from mouse feces for MNV detection using nested RT-PCR with a set of MNV-specific primers reported by Goto et al. (Exp. Anim. 58: 135-140, 2009), we found that these primers amplified not only an MNV-specific signal but also amplified a relatively weak signal with a size almost identical to that of the specific signal. Analysis of the nucleotide sequence of this amplified signal revealed that it was at least 98% identical to the exophosphatase gene of a commensal bacterium, Bacteroides vulgatus. Subsequent analysis showed that the signal amplified with a pair of nested primers was from DNA derived from B. vulgatus, which is sometimes present in SPF laboratory mouse feces, and the nested primers used were both partly homologous with the B. vulgatus nucleotide sequence. We thus designed a new set of nested RT-PCR primers that was not cross-reactive with the B. vulgatus genome. PCR products amplified by the newly designed primers were at least 89.3% identical to the MNV RNA polymerase gene in all cases. Our findings demonstrated that the primer set we designed was suitable for detecting an MNV-specific signal without cross-reacting with B. vulgatus DNA in mouse feces.
Insights
Accurate detection of murine norovirus (MNV) is crucial for immunological studies. New nested RT-PCR primers were developed to specifically detect MNV in mouse feces, avoiding cross-reactivity with Bacteroides vulgatus.
Area of Science:
- Veterinary Virology
- Molecular Diagnostics
- Microbiology
Background:
- Murine norovirus (MNV) is common in lab mice and impacts immune cells.
- MNV contamination renders mice unsuitable for immunological research.
- Accurate MNV detection is vital for reliable experimental outcomes.
Purpose of the Study:
- To develop specific nested RT-PCR primers for accurate MNV detection.
- To address cross-reactivity issues with existing primer sets.
- To ensure reliable MNV diagnostics in laboratory mouse populations.
Main Methods:
- Nested RT-PCR was employed for viral detection.
- Initial primers showed cross-reactivity with Bacteroides vulgatus DNA.
- Novel MNV-specific primers were designed and validated.
Main Results:
- Existing primers amplified both MNV and Bacteroides vulgatus DNA.
- Nucleotide sequencing confirmed cross-reactivity with Bacteroides vulgatus.
- Newly designed primers specifically amplified MNV without cross-reactivity.
Conclusions:
- The newly designed nested RT-PCR primers accurately detect MNV.
- This new primer set prevents false positives from Bacteroides vulgatus DNA.
- Improved diagnostics support the integrity of immunological research using mice.
