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While the relationship of protective human leukocyte antigen (HLA) class I alleles and HIV progression is well defined, the interaction of HLA-mediated protection and CD8 T-cell exhaustion is less well characterized. To gain insight into the influence of HLA-B*57:01 on the deterioration of CD8 T-cell responses during HIV infection in the absence of antiretroviral treatment, we compared HLA-B*57:01-restricted HIV-specific CD8 T-cell responses to responses restricted by other HLA class I alleles longitudinally after control of peak viremia. Detailed characterization of polyfunctionality, differentiation phenotypes, transcription factor, and inhibitory receptor expression revealed progression of CD8 T-cell exhaustion over the course of the infection in both patient groups. However, early effects on the phenotype of the total CD8 T-cell population were apparent only in HLA-B*57-negative patients. The HLA-B*57:01-restricted, HIV epitope-specific CD8 T-cell responses showed beneficial functional patterns and significantly lower frequencies of inhibitory receptor expression, i.e., PD-1 and coexpression of PD-1 and TIGIT, within the first year of infection. Coexpression of PD-1 and TIGIT was correlated with clinical markers of disease progression and declining percentages of the T-bethi Eomesdim CD8 T-cell population. In accordance with clinical and immunological deterioration in the HLA-B*57:01 group, the difference in PD-1 and TIGIT receptor expression did not persist to later stages of the disease.IMPORTANCE Given the synergistic nature of TIGIT and PD-1, the coexpression of those inhibitory receptors should be considered when evaluating T-cell pathogenesis, developing immunomodulatory therapies or vaccines for HIV, and when using immunotherapy or vaccination for other causes in HIV-infected patients. HIV-mediated T-cell exhaustion influences the patient´s disease progression, immune system and subsequently non-AIDS complications, and efficacy of vaccinations against other pathogens. Consequently, the possibilities of interfering with exhaustion are numerous. Expanding the use of immunomodulatory therapies to include HIV treatment depends on information about possible targets and their role in the deterioration of the immune system. Furthermore, the rise of immunotherapies against cancer and elevated cancer incidence in HIV-infected patients together increase the need for detailed knowledge of T-cell exhaustion and possible interactions. A broader approach to counteract immune exhaustion to alleviate complications and improve efficacy of other vaccines also promises to increase patients' health and quality of life.

HLA-B*5701 is the host factor most strongly associated with slow HIV-1 disease progression, although rates can vary within this group. Underlying mechanisms are not fully understood but likely involve both immunological and virological dynamics. The present study investigated HIV-1 in vivo evolution and epitope-specific CD8(+) T cell responses in six HLA-B*5701 patients who had not received antiretroviral treatment, monitored from early infection for up to 7 years. The subjects were classified as high-risk progressors (HRPs) or low-risk progressors (LRPs) based on baseline CD4(+) T cell counts. Dynamics of HIV-1 Gag p24 evolution and multifunctional CD8(+) T cell responses were evaluated by high-resolution phylogenetic analysis and polychromatic flow cytometry, respectively. In all subjects, substitutions occurred more frequently in flanking regions than in HLA-B*5701-restricted epitopes. In LRPs, p24 sequence diversity was significantly lower; sequences exhibited a higher degree of homoplasy and more constrained mutational patterns than HRPs. The HIV-1 intrahost evolutionary rate was also lower in LRPs and followed a strict molecular clock, suggesting neutral genetic drift rather than positive selection. Additionally, polyfunctional CD8(+) T cell responses, particularly to TW10 and QW9 epitopes, were more robust in LRPs, who also showed significantly higher interleukin-2 (IL-2) production in early infection. Overall, the findings indicate that HLA-B*5701 patients with higher CD4 counts at baseline have a lower risk of HIV-1 disease progression because of the interplay between specific HLA-linked immune responses and the rate and mode of viral evolution. The study highlights the power of a multidisciplinary approach, integrating high-resolution evolutionary and immunological data, to understand mechanisms underlying HIV-1 pathogenesis.

While the relationship of protective HLA class I alleles and HIV progression is well defined, the interaction of HLA-mediated protection and CD8 T-cell exhaustion is less well characterized. To gain insight in the influence of HLA-B*57:01 on the deterioration of CD8 T-cell responses during HIV infection in the absence of antiretroviral treatment, we compared HLA-B*57:01-restricted HIV-specific CD8 T-cell responses to responses restricted by other HLA class I alleles longitudinally following control of peak viremia. Detailed characterization of polyfunctionality, differentiation phenotypes, transcription factor and inhibitory receptor expression revealed progression of CD8 T-cell exhaustion over the course of the infection in both patient groups. However, early effects on the phenotype of the total CD8 T-cell population were apparent only in HLA-B*57-negative patients. The HLA-B*57:01-restricted, HIV-1 epitope-specific CD8 T-cell responses showed beneficial functional patterns and significantly lower frequencies of inhibitory receptor expression, i.e. PD-1 and PD-1/TIGIT co-expression, within the first year of infection. Co40 expression of PD-1 and TIGIT was correlated to clinical markers of disease progression and declining percentages of the T-bet(hi)/Eomes(dim) CD8 T-cell population. In accordance with clinical and immunological deterioration in the HLA-B*57:01 group, the difference in PD-1 and TIGIT receptor expression did not persist to later stages of the disease. [ABSTRACT FROM AUTHOR]