Characterization of Gag and Nef-specific ELISpot-based CTL responses in HIV-1 infected Indian individuals

Area of Science:

• Immunology
• Virology
• Vaccine Research

Background:

• Cytotoxic T lymphocyte (CTL) responses are crucial for controlling viral infections.
• Specific HIV-1 proteins, Gag and Nef, elicit distinct CTL responses influencing viral dynamics.
• Understanding these responses in diverse populations is key for therapeutic strategies.

Purpose of the Study:

• To investigate CTL responses to HIV-1 subtype C Gag and Nef proteins in antiretroviral therapy-naive Indian individuals.
• To correlate the magnitude of Gag- and Nef-specific CTL responses with plasma viral load.
• To identify immunodominant regions within Gag and Nef for potential vaccine and immunotherapy design.

Main Methods:

• Interferon-gamma (IFN-γ) ELISpot assay was employed to screen CTL responses at a single peptide level.
• Peripheral blood mononuclear cells (PBMCs) from 30 HIV-1 infected Indian individuals were analyzed.
• Responses were directed against specific peptides from HIV-1 subtype C Gag and Nef proteins.

Main Results:

• A high prevalence of CTL responses was observed: 73.3% responded to Gag and 90% to Nef antigens.
• Gag-specific CTL magnitude showed an inverse correlation with plasma viral load (r = -0.45, P = 0.001).
• Nef-specific CTL magnitude demonstrated a direct correlation with plasma viral load (r = 0.115).
• Thirteen immunodominant regions (6 in Gag, 7 in Nef) were identified.

Conclusions:

• Gag-specific CTL responses are associated with better control of HIV-1 viremia.
• Nef-specific CTL responses are linked to higher HIV-1 viral loads.
• Identifying these Gag and Nef-specific responses and epitopes in the Indian population offers insights for designing novel immunotherapies and vaccines.