A proposal for a new approach to a preventive vaccine against human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) is a more complex retrovirus, coding for several accessory proteins in addition to the structural proteins (Gag, Pol, and Env) that are found in all retroviruses. More complex retroviruses have not been isolated from birds, and simpler retroviruses have not been isolated from humans. However, the proviruses of many endogenous simpler retroviruses are present in the human genome. These observations suggest that humans can mount a successful protective response against simpler retroviruses, whereas birds cannot. Thus, humans might be able to mount a successful protective response to infection with a simpler HIV-1. As a model, a simpler bovine leukemia virus which is capable of replicating has been constructed; a simpler HIV-1 could be constructed in a similar fashion. I suggest that such a simpler HIV-1 would be a safe and effective vaccine against HIV-1.