Polyomaviruses: An overview

Polyomavirus, a small nonenveloped DNA virus, has been known to cause severe hemorrhagic cystitis primarily in recipients of bone marrow transplantation and progressive multifocal leukodystrophy in patients with HIV infection. Recently, transplant nephropathy due to BKV, a member of the polyomavirus family, has been increasingly recognized as the cause for allograft failure. Polyomavirus has also been found to be associated with various neoplastic disorders and autoimmune conditions. At present, quantitation of polyomavirus DNA in the blood, cerebrospinal fluid, and urine; identification of virus-laden "decoy cells" in urine; and histopathologic demonstration of viral inclusions in the brain parenchyma and renal tubules are the few applicable diagnostics methods. Although various antiviral agents have been tried to treat polyomavirus-related infection, current management aims at the modification and/or improvement in the hosts' immune status. In this article, the authors provide an overview of polyomaviruses and briefly introduce the topics to be discussed in greater detail in later articles by experts in the field.