Some have been tested in Phase 2b/3 clinical trials and have taught us the usefulness of HIV-1 Env proteins for protective vaccine design, the need to induce both T- and B-cell responses, and the contribution of non-neutralizing antibodies directed against the HIV-1 Env V1V2 region in the prevention of HIV-1 infection [10–12,14]. The gene discussed is ERVW-1; the disease is HIV-1 infection.