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Updated: Jul 27, 2026
Merkel Cell Polyomavirus Infection and Detection
Published on: February 7, 2019
Identification and Characterization of MmuPV1 Causing Papillomatosis Outbreak in an Animal Research Facility
Vladimir Majerciak1, Kristin E Killoran2, Lulu Yu1
1Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA.
Abstract:
Mouse papillomavirus (MmuPV1) is the first papillomavirus known to infect laboratory mice, making it an irreplaceable tool for research on papillomaviruses. Despite wide use, standardized techniques for conducting MmuPV1 animal research are lacking. In this report, we describe an unexpected MmuPV1 outbreak causing recurrent papillomatosis in a specific pathogen-free animal research facility. The infected mice displayed characteristic papillomatosis lesions from the muzzles, tails, and feet with histological signs including anisocytosis, epithelial dysplasia, and typical koilocytosis. Etiology studies showed that the papilloma tissues exhibited MmuPV1 infection with expression of viral early and late genes detected by RNA-ISH using MmuPV1 antisense probe to viral E6E7 region and antisense probe to viral L1 region. The viral L1 protein was detected by an anti-MmuPV1 L1 antibody. PCR amplification and cloning of the entire viral genome showed that the origin of the outbreak virus, named MmuPV1 Bethesda strain (GenBank Acc. No. PX123224), could be traced to the MmuPV1 virus previously used in studies at the same facility. Our data indicate that MmuPV1 could exist in a contaminated environment for a long period of time, and a standardized international animal protocol discussing how to handle MmuPV1 studies is urgently needed.
Insights
An unexpected mouse papillomavirus (MmuPV1) outbreak caused recurrent papillomatosis in a research facility. This highlights the need for standardized MmuPV1 handling protocols to prevent environmental contamination and ensure animal research integrity.
Area of Science:
- Veterinary Pathology
- Virology
- Animal Research
Background:
- Mouse papillomavirus (MmuPV1) is crucial for papillomavirus research.
- Standardized MmuPV1 research protocols are currently lacking.
- MmuPV1 research is vital for understanding papillomavirus infections.
Purpose of the Study:
- To report an unexpected MmuPV1 outbreak in a specific pathogen-free facility.
- To investigate the etiology and origin of the MmuPV1 outbreak.
- To emphasize the need for standardized MmuPV1 handling protocols.
Main Methods:
- Histopathological examination of lesions (anisocytosis, dysplasia, koilocytosis).
- RNA in situ hybridization (RNA-ISH) to detect viral E6E7 and L1 gene expression.
- Immunohistochemistry using an anti-MmuPV1 L1 antibody.
- PCR amplification and genome sequencing to trace the virus origin.
Main Results:
- Mice presented with characteristic papillomatosis on muzzle, tail, and feet.
- Histology confirmed papilloma tissues with MmuPV1 infection.
- Viral early (E6E7) and late (L1) genes were expressed.
- The outbreak strain, MmuPV1 Bethesda, was traced to prior MmuPV1 use in the facility.
- MmuPV1 can persist in contaminated environments.
Conclusions:
- MmuPV1 can cause recurrent papillomatosis and persist environmentally.
- Standardized international protocols for MmuPV1 animal studies are urgently required.
- This outbreak underscores the importance of biosecurity in animal research facilities handling MmuPV1.
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