Gag-specific immune responses after immunization with p17/p24:Ty virus-like particles in HIV type 1-seropositive individuals

Gag-specific immune responses and changes in HIV-1 RNA levels were evaluated in eight HIV-1-infected persons, in order to assess the immunotherapeutic potential of HIV-1 p17/p24: Ty virus-like particles (p24-VLP), All treated subjects showed transient and dose-dependent proliferative responses to the Ty-VLP carrier (stimulation index [SI], 2.0-119.5). Three of four individuals who received either 500 or 1000 mu g of p24-VLP also showed proliferative responses to p17 or p24 (SI, 2.0-15.7), In 2 subjects who were treated with either 500 or 1000 mu g of p24-VLP, enhanced Gag-specific CTL precursor (CTLp) frequencies were observed after immunization (10- to 14-fold), Both subjects had low baseline Gag-specific CTL activity (<25 CTLp/10(6) PBMCs), In the other participants studied no significant boosting of preexisting Gag-specific CTL responses was observed, Short-term elevation of HIV-1 RNA levels at weeks 2 and 4 was observed in two subjects treated with the highest dose of p24-VLP. However, HIV-1 RNA levels at week 24 did not significantly differ from those found in the placebo group, In conclusion, p24-VLP induced marginal Gag-specific immune responses in limited numbers of HIV-l-seropositive individuals, with some showing transient elevation of HIV-1 viral load, Further studies are needed to establish potential clinical effects of these observations.