Critical effect of Pol escape mutations associated with detrimental allele HLA-C*15: 05 on clinical outcome in HIV-1 subtype A/E infection

OBJECTIVE

The mechanism explaining the role of detrimental HLA alleles in HIV-1 infections has been investigated in very few studies. HLA-A*29:01-B*07:05-C*15:05 is a detrimental haplotype in HIV-1 subtype A/E-infected Vietnamese individuals. The accumulation of mutations at Pol 653/657 is associated with a poor clinical outcome in these individuals. However, the detrimental HLA allele and the mechanism responsible for its detrimental effect remains unknown. Therefore, in this current study we identified the detrimental HLA allele and investigated the mechanism responsible for the detrimental effect.

DESIGN AND METHODS

A T-cell epitope including Pol 653/657 and its HLA restriction were identified by using overlapping HIV-1 peptides and cell lines expressing a single HLA. The effect of the mutations on the T-cell recognition of HIV-1-infected cells was investigated by using target cells infected with the mutant viruses. The effect of these mutations on the clinical outcome was analyzed in 74 HLA-C*15:05 Vietnamese infected with the subtype A/E virus.

RESULTS

We identified HLA-C*15:05-restricted SL9 epitope including Pol 653/657. PolS653A/T/L mutations within this epitope critically impaired the T-cell recognition of HIV-1-infected cells, indicating that these mutations had escaped from the T cells. T-cell responders infected with these mutants showed significantly lower CD4 T-cell counts than those with the wild-type virus or Pol S653K/Q mutants, which are not associated with HLA-C*15:05.

CONCLUSION

The accumulation of Pol S653A/T/L escape mutants critically affected the control of HIV-1 by SL9-specific T cells and led to a poor clinical outcome in the subtype A/E-infected individuals having the detrimental HLA-C*15:05 allele.

Identification of HLA-A*3101-restricted cytotoxic T-lymphocyte response to human immunodeficiency virus type 1 (HIV-1) in patients with chronic HIV-1 infection

Virus-specific cytotoxic T-lymphocyte (CTL) responses are critical in the control of human immunodeficiency virus type 1 (HIV-1) infections. As several HIV-1 CTL epitopes restricted to many HLA types are already known, we aimed at identifying the CTL epitopes restricted by HLA-A*3101 in an effort to expand the epitope repertoire available for the development of potential T cell-mediated therapeutic measures and protective vaccines. Scanning of HIV-1 clade B SF2 strain proteins for the presence of peptides containing HLA-A*3101-binding motifs revealed 88 nine- to 11-mer peptides that had been synthesized and assayed for binding to HLA-A*3101 molecules. Peptides with medium to high HLA-binding affinity were tested for their ability to stimulate a CTL response in the peripheral blood mononuclear cells (PBMCs) from selected HIV-1-infected patients. Two of these binding peptides, Env769-779 (RLRDLLLIAAR) and Nef192-200 (KLAFHHMAR), induced peptide-specific CTLs in PBMCs from at least two of five HIV-1-seropositive individuals. CTL clones specific for the two peptides killed HLA-A*3101-expressing target cells infected with HIV-1 recombinant vaccinia virus, indicating that these peptides were naturally processed HLA-A*3101-restricted CTL epitopes. Identification of T-cell epitopes on HIV-1 proteins will increase our understanding of the role of CD8+ T cells in HIV-1 infections and assist in the design of new protective strategies.