The Major Genetic Determinants of HIV-1 Control Affect HLA Class I Peptide Presentation

Section: Discussionmentioning

confidence: 69%

Comparative Analysis of the Capacity of Elite Suppressor CD4 ⁺ and CD8 ⁺ T Cells To Inhibit HIV-1 Replication in Monocyte-Derived Macrophages

Walker-Sperling

Buckheit

Blankson

2014

“…Sera from HIV-infected individuals (Table 1) were collected, heat inactivated, and stored as previously described (18). Written informed consent was obtained from all study participants (the Montreal Primary HIV Infection Cohort [56,57] and the Canadian Cohort of HIV Infected Slow Progressors [58][59][60]), and research adhered to the ethical guidelines of the CRCHUM and was reviewed and approved by the CRCHUM institutional review board (ethics committee). Additional serum samples were acquired from HIV-1-infected individuals from Thailand who were enrolled in the HIV STAR study, as previously described (61) ( Table 2).…”

Section: Methodsmentioning

confidence: 99%

Influence of the Envelope gp120 Phe 43 Cavity on HIV-1 Sensitivity to Antibody-Dependent Cell-Mediated Cytotoxicity Responses

Prévost

Zoubchenok

Richard

et al. 2017

HIV-1-infected cells presenting envelope glycoproteins (Env) in the CD4-bound conformation on their surface are preferentially targeted by antibodydependent cellular-mediated cytotoxicity (ADCC). HIV-1 has evolved sophisticated mechanisms to avoid the exposure of Env ADCC epitopes by downregulating CD4 and by limiting the overall amount of Env on the cell surface. In HIV-1, substitution of large residues such as histidine or tryptophan for serine 375 (S375H/W) in the gp120 Phe 43 cavity, where Phe 43 of CD4 contacts gp120, results in the spontaneous sampling of an Env conformation closer to the CD4-bound state. While residue S375 is well conserved in the majority of group M HIV-1 isolates, CRF01_ AE strains have a naturally occurring histidine at this position (H375). Interestingly, CRF01_AE is the predominant circulating strain in Thailand, where the RV144 trial took place. In this trial, which resulted in a modest degree of protection, ADCC responses were identified as being part of the correlate of protection. Here we investigate the influence of the Phe 43 cavity on ADCC responses. Filling this cavity with a histidine or tryptophan residue in Env with a natural serine residue at this position (S375H/W) increased the susceptibility of HIV-1-infected cells to ADCC. Conversely, the replacement of His 375 by a serine residue (H375S) within HIV-1 CRF01_AE decreased the efficiency of the ADCC response. Our results raise the intriguing possibility that the presence of His 375 in the circulating strain where the RV144 trial was held contributed to the observed vaccine efficacy.

“…HLA class I typing was performed on genomic DNA samples extracted from blood at the time of enrollment as described previously (3). Of the 70 patients included in this study, 35 possessed protective HLA class I alleles (A*74:01, B*57, B*58:01, and B*81:01) (3,(13)(14)(15)(16)(17). These HLA alleles were selected as the principal protective alleles and are consistently the most protective that have been identified in the Durban study population (17,30,33).…”

Section: Methodsmentioning

confidence: 99%

“…HIV is able to evade immune responses by developing mutations that mediate escape from CTL recognition (6-12). In addition, the expression of certain HLA class I molecules by HIV-infected patients, such as HLA-B*27, HLA-B*57, HLA-B*58:01, HLA-B*81:01, and HLA-A*74: 01, is associated with better clinical disease outcomes in some population settings (3,(13)(14)(15)(16)(17)(18). HLA class I proteins present viral peptides on the surface of antigen-presenting cells to CTLs, and a major mechanism by which these protective alleles slow HIV disease progression is believed to be through CTL activity (18).…”

mentioning

confidence: 99%

CD8 ⁺ T Cell Breadth and Ex Vivo Virus Inhibition Capacity Distinguish between Viremic Controllers with and without Protective HLA Class I Alleles

Koofhethile

Ndhlovu

Thobakgale-Tshabalala

et al. 2016

The mechanisms of viral control and loss of viral control in chronically infected individuals with or without protective HLA class I alleles are not fully understood. We therefore characterized longitudinally the immunological and virological features that may explain divergence in disease outcome in 70 HIV-1 C-clade-infected antiretroviral therapy (ART)-naive South African adults, 35 of whom possessed protective HLA class I alleles. We demonstrate that, over 5 years of longitudinal study, 35% of individuals with protective HLA class I alleles lost viral control compared to none of the individuals without protective HLA class I alleles (P ‫؍‬ 0.06). Sustained HIV-1 control in patients with protective HLA class I alleles was characteristically related to the breadth of HIV-1 CD8 ؉ T cell responses against Gag and enhanced ability of CD8 ؉ T cells to suppress viral replication ex vivo. In some cases, loss of virological control was associated with reduction in the total breadth of CD8 ؉ T cell responses in the absence of differences in HIV-1-specific CD8 ؉ T cell polyfunctionality or proliferation. In contrast, viremic controllers without protective HLA class I alleles possessed reduced breadth of HIV-1-specific CD8 ؉ T cell responses characterized by reduced ability to suppress viral replication ex vivo. These data suggest that the control of HIV-1 in individuals with protective HLA class I alleles may be driven by broad CD8 ؉ T cell responses with potent viral inhibitory capacity while control among individuals without protective HLA class I alleles may be more durable and mediated by CD8 ؉ T cell-independent mechanisms. H IV remains a global problem, and sub-Saharan Africa continues to bear the brunt of the epidemic, accounting for 67% of the infected people worldwide (1). Understanding the mechanisms of natural viral control in HIV infection is crucial for the identification of correlates of immune protection and for the design of an effective HIV vaccine. Previous studies have linked HIV control to a number of immunological factors, particularly HIVspecific CD8 ϩ cytotoxic T lymphocytes (CTLs), which have been demonstrated to play an important role (2-5). However, virusspecific CD8 ϩ T cell immune responses are not equally effective in HIV control, as the majority of infected individuals progress to disease despite the presence of these cells. HIV is able to evade immune responses by developing mutations that mediate escape from CTL recognition (6-12). In addition, the expression of certain HLA class I molecules by HIV-infected patients, such as HLA-B*27, HLA-B*57, HLA-B*58:01, HLA-B*81:01, and HLA-A*74: 01, is associated with better clinical disease outcomes in some population settings (3,(13)(14)(15)(16)(17)(18). HLA class I proteins present viral peptides on the surface of antigen-presenting cells to CTLs, and a major mechanism by which these protective alleles slow HIV disease progression is believed to be through CTL activity (18).