Trichodysplasia spinulosa polyomavirus

Trichodysplasia spinulosa polyomavirus (TSPyV), a member of Human polyomavirus 8, was first identified in 2010 and is linked to Trichodysplasia spinulosa, a rare skin disorder affecting immunocompromised individuals. It was the eighth human polyomavirus discovered and one of four associated with disease among thirteen known as of 2015. TSPyV has a circular double-stranded DNA genome of approximately 5.2 kilobases. Initially thought to contain five genes, further studies revealed additional proteins: middle tumor antigen, tiny T, and an alternatively spliced form of large tumor antigen called ALTO.

Trichodysplasia spinulosa is a benign yet disfiguring condition characterized by hyperproliferation and enlargement of hair follicles. Unlike Merkel cell carcinoma, it is not cancerous but involves replication in the inner root sheath cells of hair follicles. Antiviral drugs like valganciclovir and cidofovir have shown effectiveness in treating this condition.

Epidemiologically, TSPyV commonly infects asymptomatic healthy adults, with seroprevalence estimates ranging from 70% to 80%. While the virus is prevalent, it rarely causes disease except in severely immunocompromised individuals. Those exhibiting symptoms have higher viral loads compared to asymptomatic carriers.