ERVW-1 and systemic lupus erythematosus: This model is supported by the differences we found between the two patient categories in the ability of their serum 9G4+ antibodies to bind HIV-1 Env as 9G4+ antibodies from most SLE patients failed to bind to HIV-1 Env, whereas 9G4+ antibodies from our cohort of PLWH showed robust binding to HIV-1 Env.