The BK virus is a member of the polyomavirus family. It has been suggested that this virus may be transmitted through respiratory fluids or urine, since infected individuals periodically excrete virus in the urine. BK viral infections are typically asymptomatic in healthy individuals, however very mild symptoms may appear including mild respiratory infections and fever. Infections with BK virus in immunocompromised or immunosupressed patients are much more severe and may involve renal dysfunction. In fact, in kidney transplant patients the immunosupressive drugs required for the transplant may allow the virus to replicate within the graft, resulting in a disease called BK virus nephropathy (BKVN). The JC virus is a type of human polyomavirus and is very common in the general population, infecting 70 to 90% of humans. Most people acquire JCV in childhood or adolescence. Typically the infection is subclinical and no of consequence in individuals with healthy immune systems. The initial site of infection may be the tonsils or the gastrointestinal tract, and the virus then remains latent in the gastrointestinal tract. JCV can also infect the tubular epithelial cells in the kidneys, where it continues to reproduce, shedding virus particles in the urine. Also, JCV can cross the blood-brain barrier into the central nervous system. JCV is known to cause the usually fatal progressive multifocal leukoencephalopathy (PML) by destroying oligodendrocytes in the brain in immunodeficient or immunosuppressed individuals. The JC and BK viruses are very similar, with their genomes sharing 75% homology. It is however important to differentiate between the viruses due to the differences in pathology and especially the invariably fatal outcome of PML which is only caused by the JC virus.

For research use only and NOT intended for in vitro diagnostics.