Do cytotoxic T lymphocytes clear some HIV/SIV infections?

Early work on the roles of cytotoxic T lymphocytes (CTLs) in acute viral infections in animal models showed that i) the clearance of virus coincided with the increase in CTL activity rather than specific antibody levels, ii) transfer of CTLs after infection could protect from a lethal dose of virus, and iii) in primed, compared to naive, animals, CTL activity appeared 1-3 days earlier after a challenge infection. There is now a series of findings with individuals who have been exposed to HIV but are HIV-seronegative that suggest a protective role for CTLs. Usually after in vitro culture, HIV specific CTLs have been isolated from i) infants born of infected mothers, ii) long-time partners of HIV-infected people, iii) some prostitutes in Africa, and iv). Most recently, 7/20 seronegative health care workers exposed once to HIV have been shown to possess HIV env-specific CTLs. The findings suggest that CTLs (a type I T cell response) may rapidly clear a low dose of HIV. Experiments with SIV are proposed that may provide more direct supporting data for this possibility.