Mouse Polyoma Virus

Mouse Polyomavirus (MPyV), originally discovered by Ludwik Gross in 1953, is a small, non-enveloped DNA virus belonging to the Polyomaviridae family. It stands as one of the most historically significant and well-studied models in tumor virology and viral pathogenesis. This family of viruses includes members such as BK polyomavirus (BKV), JC virus (JCPyV), murine polyomavirus (PY), and monkey vacuolar virus (SV40). PY virus was first isolated from mouse leukemia virus by Gross in 1953 and can induce multiple tumors in neonatal rodents; SV40 was found in the kidney cells of rhesus monkeys and its host is primates. Human viruses BKV and JCPyV are isolated from kidney transplant patients and brain disease patients, respectively. After infection, they often remain in a latent state and can be activated under immunosuppression to cause kidney disease or progressive multifocal leukoencephalopathy. The phenomenon of BK virus spreading through urine and integrating its genome into host cells has been found in cases of urothelial carcinoma. The viral structural proteins VP1 and VP2 participate in capsid assembly, and the early encoded large T antigen is associated with cell transformation.

Figure 1. Structure of Mouse Polyoma Virus. (Cianci G,et al, 2025)

General Biological Characteristics

The polyoma virus family includes polyoma viruses (PY), SV40, BKV, JKV, etc., and their biological characteristics are also different. PY virus was isolated by Gross in 1953 from the AKR mouse leukemia virus transmission process. It is widely distributed in a latent form between laboratory and wild mice. Young mice are infected due to contact with adult mouse urine or saliva, and generally do not induce tumors under natural conditions Newborn mice, rats, hamsters, rabbits, guinea pigs, etc. In 1957, Steward and Eddy first successfully cultured PY in mouse embryonic fibroblasts, and subsequently discovered that PY could also transform mouse and hamster fibroblasts. DNA isolated from PY also had the ability to transform cells.

SV40 Virus

The SV40 virus lives in the kidney cells of rhesus monkeys. The virus grows in these monkey kidney cells but does not cause significant cellular damage. However, adding the culture medium of rhesus kidney cells to the culture medium of African green monkey kidney cells causes the latter cells to produce obvious vacuoles. This virus is called simian vacuolating virus and is now commonly referred to as SV40. Injecting isolated SV40 or DNA extracted from SV40 into newborn hamsters can induce sarcoma. SV40 can induce transformation in cultured hamster, rat, monkey, and other cells in vitro SV40 enters the sensitive monkey kidney nucleus and matures, producing a large number of viral particles that cause cell lysis and death. This process takes about 24-48 hours at 37 ℃ BKV is a virus isolated from the urine of a patient with suppressed immune function after human kidney transplantation. It can induce tumors in newborn hamsters and mice, and can transform hamster, rat, mouse, rabbit, and African green monkey cells in vitro. BKV's DNA can also transform rat and hamster cells JCV is a virus isolated from the brain tissue of a human patient with multiple focal white matter disease (PML), which can induce glioma in newborn hamsters JCV's DNA induces transformation of primary cultured hamster glial cells.

Genomic structure

Both PY and SV40 virus particles have a 20 sided stereosymmetric structure, with the same diameter, number of capsids, and DNA molecular weight, but with differences in protein composition SV40DNA contains 5243 base pairs, while PY virus is a circular double stranded DNA molecule composed of 5292 base pairs The isolated and purified viral DNA is infectious and can transform cells and induce tumors in hamsters in vitro A detailed study has been conducted on the structure of the SV40 virus, with a clear understanding of its genome nucleotide sequence analysis, gene localization, and various proteins involved in replication. The SV40 virus genome is divided into 100 equal parts using the EcoRl endonuclease cleavage site as the 0 point, and the Ori point is the starting point for bidirectional DNA replication The early coding process within the SV40 virus genome is counterclockwise, and the encoded proteins (large T and small T antigens) are related to inducing host cell transformation before viral DNA production. The late coding region process is clockwise and encodes three viral capsid proteins, VP1, VP2, and CP3, after the start of viral DNA replication. These proteins are structural proteins of the virus and do not participate in the process of cell transformation The physical structure diagram of PY is similar to SV40, which is also a circular structure, but the origin of ori is different, and the early coding process is clockwise, encoding three proteins (large T, medium T, and small T antigens).

Anti-Polyomavirus Antibody

Polyomavirus Antigens