Adult acquired chronic intestinal pseudo-obstruction (CIP) has mainly been attributed to secondary forms of pseudo-obstruction associated with systemic inflammatory disorders such as progressive systemic sclerosis and systemic lupus erythematosus, endocrine disorders and neurological disorders. However, recent case series from large tertiary centres have described adults without any known predisposing disease, so-called idiopathic CIP.1 2 In this issue of Gut, Selgrad et al (see page 25)3 report their findings of JC (John Cunningham) virus proteins in glial cells of the myenteric plexus in 7/10 adult patients with idiopathic CIP. These findings seem to implicate a role for JC virus, a DNA virus that belongs to the family of polyomaviruses, in the pathogenesis of CIP.

JC virus is the causative agent in progressive multifocal leucoencephalopathy (PML),4 a disease that almost exclusively occurs in immnocompromised patients. Today HIV/AIDS is the most prevalent state of deficient cell-mediated immunity associated with a risk for developing PML. In recent years PML has also occurred in patients treated with certain biological drugs such as natalizumab, an antibody against the cellular adhesion molecule α4-integrin, and rituximab, an antibody against the cluster of differentiation 20 (CD20), which is widely expressed on the surface of B cells.5 Reactivation of a latent JC virus infection is believed to be the main mechanism by which the virus ultimately can …