Nef-specific CD8+ T cell responses contribute to HIV-1 immune control

Area of Science:

• Immunology
• Virology
• Genetics

Background:

• Nef-specific CD8+ T-cell responses are implicated in controlling viremia in SIV-macaque models.
• In human immunodeficiency virus (HIV) infection, Nef recognition is dominant in acute stages, but breadth of T-cell responses to Nef doesn't correlate with viral control in chronic infection.
• Previous analyses of Nef-specific T-cell responses are confounded by epitope overlap, necessitating alternative assessment methods.

Purpose of the Study:

• To investigate the association between Nef polymorphisms, HLA-B alleles, and viral load in chronic HIV-1 infection.
• To determine if specific Nef epitopes targeted by CD8+ T cells contribute to viral suppression.
• To assess the potential of Nef as a target in HIV T-cell vaccine candidates.

Main Methods:

• Analysis of >700 individuals with chronic C-clade HIV-1 infection.
• Assessment of HLA-B-selected polymorphisms within the Nef protein and their predicted fitness cost to the virus.
• Correlation of HLA-B alleles with viral loads.
• Identification of CD8+ T-cell epitopes restricted by protective HLA Class I alleles and comparison with SIV-specific epitopes.
• Utilized peptide-MHC I tetramers for distinguishing specific HIV-specific responses within Nef.

Main Results:

• Over 50% of HLA-B-selected Nef polymorphisms are associated with a predicted fitness cost to HIV-1.
• Specific HLA-B alleles driving selection within Nef are linked to lower viral loads.
• CD8+ T-cell epitopes restricted by protective HLA Class I alleles in Nef substantially overlap with effective SIV-specific epitopes.
• Targeting specific Nef epitopes with CD8+ T cells contributes to HIV suppression.

Conclusions:

• CD8+ T-cell targeting of specific Nef epitopes plays a role in controlling HIV-1 viremia.
• The findings suggest that Nef-specific T-cell responses, particularly those targeting conserved epitopes, may be crucial for immune control.
• A re-evaluation of Nef's potential inclusion in HIV T-cell vaccine strategies is warranted.