Institutional review boards in Providence and Bamako, Mali, approved the informed consent procedures and research protocols at each of the sites. Informed consent was obtained prior to obtaining all samples for this study. Patient study cohorts were from two

geographically inhibitors distinct locations: Providence, Rhode Island, and Bamako, Mali. The Providence study subjects belonged to two cohorts (cohort #1 and cohort #2) of long-term slow or non-progressors (CD4 > 350 for >10 years with minimal or no treatment) or from chronically HIV-infected patients (CD4 > 350 and not on treatment). Subjects in cohort one were recruited from an HIV clinic at the Miriam Hospital in Providence, Rhode Island, and were used to validate epitopes selected selleck compound DAPT cost in 2002. Subjects in cohort #2 were HIV-seronegative donors from the Rhode Island Blood Center (RIBC) and were used to validate epitopes initially identified in 1997 and reselected in 2002. Subjects in cohort #3 were HIV-1 infected, otherwise healthy (CD4 > 350) volunteers recruited from the Bloc Espoir clinic situated in Sikoro, Bamako, Mali; these subjects were used to validate epitopes that were either newly identified or reselected for study inclusion in 2009. HLA typing was performed by the Transplant Immunology Laboratory at Hartford Hospital and the Faculty of Science and Technology at the University of Bamako using the Micro SSP HLA Class I DNA typing tray

(One Lambda Inc., Canoga Park, CA). The frequency of epitope-specific T lymphocytes was determined using Mabtech® IFNγ ELISpot kits according to the manufacturer’s instructions (Mabtech, Sweden). Washed PBMCs from each donor were added at 2.5 × 105 cells per well to 96-well ELISpot plates pre-coated with anti-IFNγ antibody. Individual peptides were added to the ELISpot plate at 10 μg/ml, Histamine H2 receptor as well as positive controls PHA (10 μg/ml) and the CEF peptide pool (10 μg/ml). In assays done in Mali in 2009–2010, the CEF peptide pool was replaced with a pool of all tested HIV peptides. Six to twelve wells of PBMCs per plate were cultured without peptide to measure background. The ELISpot plates were incubated overnight at 37˚C, and then

washed with PBS. Following the washes, biotinylated anti-IFNγ was added, followed by streptavidin-HRP. ELISpot plates were developed by the addition of filtered TMB substrate. The frequency of antigen-specific cells was calculated as the number of spots per 106 PBMCs seeded. Responses were considered positive if the number of spots was at least twice background and was also greater than twenty spots per million cells over background (one response over background per 50,000 PBMCs). The relatively lower number of spots seen can be expected when stimulating cells directly ex vivo with peptide, as compared to the larger responses seen when cells are stimulated with whole protein or peptide, incubated for several days, and then re-stimulated.