title: The HIV-1 antisense protein (ASP) induces CD8 T cell responses during chronic infection.
abstract: BACKGROUND
  CD8+ T cells recognize HIV-1 epitopes translated from a gene's primary reading frame (F1) and any one of its five alternative reading frames (ARFs) in the forward (F2, F3) or reverse (R1-3) directions. The 3' end of HIV-1's proviral coding strand contains a conserved sequence that is directly overlapping but antiparallel to the env gene (ARF R2) and encodes for a putative antisense HIV-1 protein called ASP. ASP expression has been demonstrated in vitro using HIV-transfected cell lines or infected cells. Although antibodies to ASP were previously detected in patient sera, T cell recognition of ASP-derived epitopes has not been evaluated. We therefore investigated the ex vivo and in vitro induction of ASP-specific T cell responses as a measure of immune recognition and protein expression during HIV-1 infection.
  
  
  RESULTS
  A panel of overlapping peptides was initially designed from the full-length ASP sequence to perform a global assessment of T cell responses. Recognition of ASP-derived antigens was evaluated in an IFN-γELISpot assay using PBMCs from HIV-1 seropositive and seronegative individuals. Eight of 25 patients had positive responses to ASP antigens and none of the seronegative donors responded. As a complimentary approach, a second set of antigens was designed using HLA-I binding motifs and affinities. Two ASP-derived peptides with high predicted binding affinities for HLA-A*02 (ASP-YL9) and HLA-B*07 (ASP-TL10) were tested using PBMCs from HIV-1 seropositive and seronegative individuals who expressed the matching HLA-I-restricting allele. We found that HLA-I-restricted ASP peptides were only recognized by CD8+ T cells from patients with the relevant HLA-I and did not induce responses in any of the seronegative donors or patients who do not express the restrictive HLA alleles. Further, ASP-YL9-specific CD8+ T cells had functional profiles that were similar to a previously described HLA-A*02-restricted epitope (Gag-SL9). Specific recognition of ASP-YL9 by CD8+ T cells was also demonstrated by tetramer staining using cells from an HLA-A*02 HIV-infected patient.
  
  
  CONCLUSIONS
  Our results provide the first description of CD8+ T cell-mediated immune responses to ASP in HIV-1-infected patients, demonstrating that ASP is expressed during infection. Our identification of epitopes within ASP has implications for designing HIV vaccines.
authors: Anne
authors: A
authors: Bet
authors: Emmanuel Atangana
authors: EA
authors: Maze
authors: Anju
authors: A
authors: Bansal
authors: Sarah
authors: S
authors: Sterrett
authors: Antoine
authors: A
authors: Gross
authors: Stéphanie
authors: S
authors: Graff-Dubois
authors: Assia
authors: A
authors: Samri
authors: Amélie
authors: A
authors: Guihot
authors: Christine
authors: C
authors: Katlama
authors: Ioannis
authors: I
authors: Theodorou
authors: Jean-Michel
authors: JM
authors: Mesnard
authors: Arnaud
authors: A
authors: Moris
authors: Paul A
authors: PA
authors: Goepfert
authors: Sylvain
authors: S
authors: Cardinaud
mesh_terms: D000328:Adult; D000368:Aged; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D015331:Cohort Studies; D058501:Enzyme-Linked Immunospot Assay; D005260:Female; D015870:Gene Expression; D015488:HIV Antigens / Q000096:biosynthesis / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology* / Q000502:physiology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D014764:Viral Proteins / Q000096:biosynthesis / Q000276:immunology*; D014779:Virus Replication
chemical_list: D015488:HIV Antigens; D014764:Viral Proteins