Retroviruses and chronic arthritis. Possible significance of some recent observations

Retroviruses have been proposed as etiologic agents for the development of chronic arthritis in humans. The arthritis seen in goats infected by caprine arthritis encephalitis virus and the spontaneous arthritis of inbred MRL/l mice illustrate how retroviruses may cause the development of a disorder closely resembling human rheumatoid arthritis. Several investigators have searched for evidence of retrovirus infection in patients with chronic arthritis, but in most cases the results have been disappointing. However, in 1983, Iversen isolated a virus-like particle from a patient with psoriasis. The particle had a buoyant density in sucrose and a protein composition that closely resembled murine and primate retroviruses. Particle proteins participate in immune complex formation in psoriasis, in psoriatic arthritis, and in ankylosing spondylitis. Particle proteins are also present in deposits in psoriatic lesions and in affected synovial tissue resembling immune complex deposits. The possible role for retrovirus-like antigens in the inflammatory process in psoriasis and seronegative arthritis is discussed.