One study subject responded to more than 90% of the epitopes tested; although the most recent viral load MLN2238 molecular weight was not available for this particular donor during

the study time period, this type of immune response could also be expected in earlier stages of infection. Due to delays in diagnosis, not all subjects recruited in Mali after their first positive HIV test were identified as HIV infected at an early stage of disease. The one subject who did not respond to any of the 31 epitopes tested in ELISpot assays (data not shown) had a very high viral load (445,000 copies/ml) and low CD4+ T cell count that would be more typical of chronic, untreated infection, a condition that also contributes to lack of response, likely leading to the lack of positive IFNγ responses in ELISpot assays. While 95% of the selected epitopes were positive in at least one subject in either Providence or Mali, no single epitope was immunodominant within cohorts or across cohorts.

This lack of immunodominance illustrates the importance of including a broad array of epitopes for the development of a globally relevant vaccine [78], [79] and [80]. There were only three predicted epitopes that did not elicit a positive response in this set of peptides; two of these epitopes (POL-1007 and POL-1016) have been published by other groups, one as a class II epitope and the other for a different HLA restriction (Table 1), calling into question the www.selleckchem.com/products/Cisplatin.html possibility that either these epitopes were not correctly predicted (by EpiMatrix) or were not properly processed or presented on HLA-A2. POL-1007 did bind with very high affinity to HLA-A2 in vitro, which supports its identification as an HLA-A2 epitope. The third epitope for which no response was detected is a novel epitope identified in our 2009

analysis, VPU-3009. The lack of immune response to this epitope may be a function of its low binding affinity to HLA-A2. Epitope-based vaccines containing epitopes restricted by six “supertype” HLA, such as HLA-A2, are believed to be the best approach to generate broad T-cell responses with the greatest possible coverage of the human population tuclazepam [47] and [48]. In this paper, we identified 38 potential HLA-A2 epitopes for inclusion in our GAIA or other pan-HLA-reactive HIV-1 vaccines, and of these, 36 are good candidates. In work published previously, our group selected and confirmed epitopes immunogenic for HLA-B7 [32] and HLA-A3 [48], and a prior publication by our group describes the validation of promiscuous “immunogenic consensus sequence” class II epitopes in Providence and Bamako [49]. In addition to their remarkable conservation across years, the utility of the HLA-A2 epitopes described here is also supported by their aggregate conservation of 48% and 45% across countries and clades, respectively (Fig. 2). While it appears that HLA-A2 haplotypes are less equipped to fight HIV due to a low binding affinity for conserved epitopes, Altfeld et al.