Murine polyomavirus
![A rendering of an icosahedral viral capsid comprising 72 pentamers of VP1, colored such that areas of the surface closer to the interior center appear blue and areas further away appear red.](/Images/godic/202501/28/Mpyv_colorbydepth4220.png")
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![A capsid structure colored to illustrate the assembly of the icosahedral architecture from VP1 pentamers. Each symmetry-related VP1 monomer is shown in a different color. From PDB: 1SIE.](/Images/godic/202501/28/Mpyv_colorbychain4221.png")
![Micrograph of a thin section of a cell infected with MPyV illustrating the structure of the virus factories in which new virions are produced. Red indicators point to tubular structures (arrow: empty tubule; arrowhead: filled tubule) and blue indicators point to virions (arrow: empty virion; arrowhead: filled virion). The dense center of the filled structures likely indicates the presence of virus genomic DNA.[25]](/Images/godic/202501/28/Crop_mpyv_erickson_2012_plospathogens4221.png")
Murine polyomavirus (also known as mouse polyomavirus or Polyomavirus muris, and in older literature SE polyoma or parotid tumor virus; abbreviated MPyV) is an unenveloped double-stranded DNA virus of the polyomavirus family. The first member of the family discovered, it was originally identified by accident in the 1950s. A component of mouse leukemia extract capable of causing tumors, particularly in the parotid gland, in newborn mice was reported by Ludwik Gross in 1953 and identified as a virus by Sarah Stewart and Bernice Eddy at the National Cancer Institute, after whom it was once called "SE polyoma". Stewart and Eddy would go on to study related polyomaviruses such as SV40 that infect primates, including humans. These discoveries were widely reported at the time and formed the early stages of understanding of oncoviruses.