JC and BK Polyomaviruses (JCV & BKV)

Causative Agents

BK and JC viruses (BKV and JCV) are Polyomaviruses belonging to Polyomaviridae family. BKV and JCV are composed of an icosahadral viral particle (virion) containing 5000 base pair double-stranded circular DNA molecule and surrounded by a protein capsid. These viruses do not possess a lipid envelope. BKV and JCV infections are asymptomatic as they remain latent in about 90% of the main human population and may lead to infections resulting in severe diseases such as hematuria, hemorrhagic cystisis, ureteric stenosis, etc once they become reactivated upon suppression of the immune system. There are 7 distinct genotypes of JC and 4 of BK classified.


Most of the primary polyomavirus infections occur during childhood. Serological studies suggest that more than 70% of adults possess antibodies against BK or JC virus. There are serological evidences suggesting the reactivation of the JCV and BKV viruses during the pregnancy period of 5-10 % of the women.

Modes of Transmission

Although little is known about the route-of-transmission among humans, high infection rate suggests airborne transmission. Abundance of JCV and BKV in sewages also suggests transmission via contaminated food and water. Semen, blood products and organ transplantation, particularly renal allografts are other potential routes.


The diagnosis and monitoring of the BK and JCV infections are managed through histological and cytological tests with the help of high electron and fluorescence microscopy. Also the serological methods (haemagglutination inhibition test, ELISA, RIAs) based on the detection of antibodies against polyomaviruses are used widespread. Early diagnosis of BK and JCV reactivation is paramount for prevention of the possible severe diseases that even positively impacts organ survival.

Detecting BKV and JCV DNA in a multitude of specimen types using polymerase chain reaction (PCR) is the most reliable and quick method with highest sensitivity and specificity.

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