Human polyomavirus 2

Human polyomavirus 2 (HPyV2), also known as BK virus, is a member of the Polyomaviridae family of viruses. It is a DNA virus that is ubiquitous in the human population, typically infecting individuals in early childhood and remaining latent in the body. The virus is named after the initials of the patient from whom it was first isolated in 1971.

History

Human polyomavirus 2 was first discovered in 1971 in the urine of a renal transplant patient named B.K. The virus was subsequently named after the patient's initials. Since its discovery, HPyV2 has been the subject of extensive research due to its association with severe disease in immunocompromised individuals.

Virology

HPyV2 is a small, non-enveloped virus with a circular, double-stranded DNA genome. The virus is part of the Polyomaviridae family, which also includes the closely related JC virus. The genome of HPyV2 encodes for six proteins, three of which are involved in viral replication and three of which are involved in the assembly of the viral capsid.

Epidemiology

HPyV2 is ubiquitous in the human population, with seroprevalence rates of up to 90% reported in adults. The virus is typically acquired in early childhood and remains latent in the body, particularly in the urinary tract. Reactivation of the virus can occur in immunocompromised individuals, leading to severe disease.

Clinical significance

In immunocompetent individuals, infection with HPyV2 is typically asymptomatic. However, in immunocompromised individuals, such as those with HIV/AIDS or those who have undergone organ transplantation, reactivation of the virus can lead to severe disease. This includes polyomavirus-associated nephropathy (PVAN), a serious condition that can lead to graft loss in kidney transplant recipients, and hemorrhagic cystitis, a condition characterized by inflammation and bleeding in the bladder.

Treatment and prevention

There is currently no specific antiviral treatment for HPyV2 infection. Management of the infection in immunocompromised individuals typically involves reducing immunosuppression, if possible. Prevention of HPyV2 infection is difficult due to the high prevalence of the virus in the population. However, regular monitoring of viral load in at-risk individuals can help to identify reactivation of the virus and guide management decisions.

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