Microbiology
Summary
The Polyomaviridae family, encompassing both the JC virus and the BK virus, are naked, circular, double-stranded DNA viruses. The JC virus is notorious for causing progressive multifocal leukoencephalopathy (PML), a demyelinating disease affecting the white matter of the brain, marked by non-enhancing multifocal brain lesions. PML is especially prevalent among immunocompromised patients, such as those with HIV. Particularly, HIV patients with a CD4+ count below 200 are at a heightened risk, leading to a notable increase in the incidence of JC virus infections in this population.
On the other hand, the BK virus is primarily associated with complications post organ transplantation. When the latent infection of the BK virus reactivates, usually due to immunosuppression following an organ transplant, it can cause nephropathy. This nephropathy is most often observed after kidney and bone marrow transplants. Additionally, immunocompromised patients with a BK virus infection can develop hemorrhagic cystitis, a painful urinary condition.
Lesson Outline
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FAQs
JC virus, also known as the John Cunningham virus, and BK virus are both members of the Polyomaviridae family. They are DNA viruses that exist commonly and harmlessly in the population, but can cause severe diseases in immunocompromised individuals.
Transplant patients are often on immunosuppressive therapy to prevent their body from rejecting the transplanted organ. This weakened immune system can allow JC and BK viruses, which commonly reside in the body without causing symptoms, to become active and cause severe diseases such as progressive multifocal leukoencephalopathy (caused by JC virus) and BK-virus nephropathy.
Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal disease caused by the reactivation of the JC virus in immunocompromised individuals. PML affects the white matter of the brain and leads to inflammation and damage to nerve cells, causing progressive neurological symptoms.
BK virus-associated nephropathy (BKVAN) is a complication caused by the reactivation of BK virus in kidney transplant patients. The virus infects and damages the transplanted kidney cells, leading to graft loss in severe cases. Timely diagnosis and reduction in immunosuppression are the key to management of BKVAN.
