HIV vaccines

To date the NIAID sponsored AIDS Vaccine Evaluation Group (AVEU) has enrolled over 1000 patients into Phase I/II clinical trials of candidate HIV vaccines. 8 different envelope products have been evaluated including two gp160 preparations, two subunit gp120 products, one yeast derived gp120, one vaccinia gp160, 1 canarypox gp160, and one envelope peptide based vaccine. All the vaccines have been immunogenic and adverse effects have been limited to transient local reactions. Direct comparison of immune responses is not possible in all cases due to varying stages of development, the varying doses of vaccine and the different adjuvants employed in the products. Overall, the two gp120 products have proven to elicit the highest neutralising antibody titers among health seronegative vaccines. Over 90% of recipients receiving a 0, 1, 6 month regimen have detectable neutralising responses; the mean neutralising titer average about 1:100, about 5-fold lower than that seen with persons with naturally acquired HIV infection. T cell lymphoproliferative resposes are elicited by all of these vaccines However, none of the subunit vaccines alone have elicited detectable CD8+ cytolytic activity to HIV envelope (0 of 40 tested). However, 2 of 8 vaccinia naive individuals who have received a regimen consisting of priming with a vaccinia recombinant and boosting with a gp160 subunit protein have had detectable persistent CD8+ CTLs. A detailed description of the above Phase I and II trials will be given.