JC Polyomavirus: How It Destroys the Myelin Sheath and Causes Progressive Multifocal Leukoencephalopathy (PML)
The JC Polyomavirus (JCPyV) , also known as the John Cunningham virus , is one of the most common viruses in humans. It is estimated that up to 80% of adults worldwide have been infected, usually during childhood. For the vast majority of people, the infection causes no symptoms and remains harmless throughout life. After the initial infection, the virus enters a latent (inactive) state , residing primarily in the kidneys, bone marrow, and lymphoid tissues . A healthy immune system keeps the virus under tight control, preventing it from causing disease. JC Polyomavirus (JCPyV) is strongly regulated by epigenetic mechanisms , particularly modifications of the histone proteins around which its DNA is wrapped. After infecting a human cell, the virus forms a small chromatin structure called a viral minichromosome , allowing it to use the host cell's epigenetic machinery to remain dormant or become reactivated. Although JCPyV exhibits some DNA epigenetic markers, its activity is contro...