Polyoma virus is a small DNA tumor virus that causes various diseases and infections in humans and animals. Some of the synonyms for the polyoma virus are simian virus 40, JC virus, BK virus, and murine polyomavirus. JC virus is commonly found in the kidneys and urinary tract, and can lead to progressive multifocal leukoencephalopathy. BK virus is known to cause kidney infections and transplant failure, while simian virus 40 has been linked to mesothelioma and brain tumors. Murine polyomavirus, on the other hand, is commonly found in laboratory mice and can cause tumors. The various synonyms for polyoma virus reflect the different strains and specific diseases caused by this virus.