Antibody response to rubella virus antigen and structural proteins in retinitis pigmentosa

Elevated serum ELISA IgG antibodies to rubella virus (RV) were found by three independent determinations in 41 (72%) of 57 adults with the retinal degeneration retinitis pigmentosa, while antibody responses to five other common neurotropic viruses were normal. However, these patients lacked clinical signs of active RV infection or known recent RV exposure, and 56 lacked IgM anti-RV antibody. Unusual relative percentages of IgG antibody to RV structural proteins compared with those of controls were found in patients' sera by radioimmunoprecipitation assay. For retinitis pigmentosa patients, percentage of RV envelope glycoprotein E1 antibody was similar to, of RV envelope glycoprotein E2 antibody was greater than, and of antibody to RV nucleocapsid C protein was lower than control percentages. Abnormal immunity to RV was also suggested by a lack of increased proliferation of lymphocytes to RV antigen despite elevated anti-RV antibody in patients with retinitis pigmentosa. Not associated with age or particular genetic pattern, these divergences from normal immunity suggest an unusual association between RV proteins and retinitis pigmentosa.