BKV is a highly prevalent small nonenveloped virus with a closed circular double stranded DNA genome. BKV is a human polyomavirus which belongs to the papovaviridae family. Primary exposure to BKV occurs in childhood resulting in 80-90% of adults having developed antibodies to BKV. The majority of BKV symptoms are asymptomatic or minimally symptomatic. After primary infection the virus is thought to remain latent in immunocompetent individuals.¹

Viral reactivation occurs in immunocompromised individuals, occurring frequently in renal transplant patients and hematopoietic stem cell transplant (HSCT) patients, with nephropathy occurring in 5% of renal transplant patients within one year of transplantation. Late onset haemorrhagic cystitis occurs in 6-29% of HSCT recipients within 2 months of transplantation.²

Quantitative nucleic acid amplification testing from plasma and urine samples is an important laboratory marker for the diagnosis and monitoring of BKV infection in transplant patients.