Collaboration of a detrimental HLA-B*35:01 allele with HLA-A*24:02 in co-evolution of HIV-1 with T-cells leading to poorer clinical outcomes.

Although mutant-specific T-cells are elicited in some individuals infected with HIV-1 mutant viruses, the detailed characteristics of these T-cells remain unknown. A recent study showed that the accumulation of strains expressing Nef135F, which were selected by HLA-A*24:02-restricted T-cells, was associated with poor outcomes in individuals with the detrimental HLA-B*35:01 allele, and that HLA-B*35:01-restricted NefYF9(Nef135-143)-specific T-cells failed to recognize target cells infected with Nef135F mutant viruses. Here we investigated HLA-B*35:01-restricted T-cells specific for the NefFF9 epitope incorporating the Nef135F mutation. Longitudinal TCR clonotype analysis demonstrated that 3 types of HLA-B*35:01-restricted T-cells (wild type-specific, mutant-specific, and cross-reactive) with different T-cell repertoires were elicited during the clinical course. HLA-B*35:01+ individuals possessing wild type-specific T-cells had a significantly lower pVL than those with mutant-specific and/or cross-reactive T-cells, even though the latter T-cells effectively recognized the mutant virus-infected cells. These results suggest that mutant-specific and cross-reactive T-cells could only partially suppress HIV-1 replication in vivo. Ex vivo analysis of the T-cells showed higher expression of PD-1 on cross-reactive T-cells and lower expression of CD160/2B4 on the mutant-specific T cells than other T-cells, implying that these inhibitory and stimulatory molecules are key to the reduced function of these T-cells. In the present study, we demonstrate that mutant-specific and cross-reactive T-cells do not contribute to suppression of HIV-1 replication in HIV-1-infected individuals, even though they have the capacity to recognize mutant virus-infected cells. Thus, the collaboration of HLA-A*24:02 with the detrimental allele HLA-B*35:01 resulted in the co-evolution of HIV-1 alongside virus-specific T-cells, leading to poorer clinical outcomes. Importance HIV-1 escape mutations are selected under pressure from HIV-1-specific CD8+ T-cells. Accumulation of these mutations in circulating viruses impairs control of HIV-1 by HIV-1-specific T-cells. Although it is known that HIV-1-specific T-cells recognizing mutant virus were elicited in some individuals infected with mutant virus, the role of these T-cells remains unclear. Accumulation of Phenylalanine at HIV-1 Nef135 (Nef135F), which is selected by HLA-A*24:02-restricted T-cells, led to poor clinical outcome in individuals carrying the detrimental HLA-B*35:01 allele. In the present study, we found that HLA-B*35:01-restricted mutant-specific and cross-reactive T-cells were elicited in HLA-B*35:01+ individuals infected with Nef135F mutant virus. These T-cells could not effectively suppress HIV-1 replication in vivo even though they could recognize mutant virus-infected cells in vitro. Mutant-specific and cross-reactive T-cells expressed lower levels of stimulatory molecules and higher levels of inhibitory molecules, respectively, suggesting a potential mechanism whereby these T-cells fail to suppress HIV-1 replication in HIV-1-infected individuals.