Department of Microbiology, All India Institute of Medical Sciences, New Delhi-110012, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
The HIV-specific T-cell immune responses directed against a wide range of HIV-1 antigens are associated with the control of viral replication during chronic HIV infection. It is important to characterize these responses with the aim of identifying protective correlates of immunity to control HIV-1 infection in Indian population. We performed a comprehensive analysis of the breadth and magnitude of T-cell responses directed at HIV-1 subtype C Gag, one of the most targeted conserved HIV-1 proteins and Nef, one of the earliest genes expressed during the viral life cycle. IFN-g ELI Spot assay and intracellular cytokine staining were used to quantify the CD4+ and CD8+ T-cell responses to HIV-1 gag and nef at single peptide level. Stronger and broader CD8 T-cell responses were recognized, contrasting with the weaker and narrower CD4 T-cell responses with regard to Gag protein subunits. The p24-Gag was identified as the most frequently recognized subunit protein with the greatest magnitude of both CD4+ and CD8+ T-cell responses. The magnitude of the HIV-specific IFN-ã responses was observed to be higher than the corresponding IL-2 response, indicating the persistence of antigenic load in chronically infected Indian population due to the probable dysfunction of HIV-specific, IFN-gamma-secreting CD8 T cells in absence of IL-2 help. The central conserved region of the Nef was most frequently targeted region in the studied population. All the identified immunodominant regions also correlated with HIV Immunology database (Los Alamos) indicating the importance of Gag and Nef -specific responses in multi-clade vaccine approach.
