T-cell Epitopes Identified by BALB/c Mice Immunized with Vaccinia Expressing HIV-1 Gag lie within immunodominant Regions Recognized by HIV-infected Indian Patients

BACKGROUND: Human immunodeficiency virus (HIV) antigens from transmitted strains of HIV would prove crucial in vaccine designing for prevention of HIV infection. Immune response generated by Vaccinia construct expressing the HIV-1 gag gene from transmitted Indian HIV-1 subtype C strain (Vgag) in BALB/c mice is reported in the present study along with the identification of epitopes responsible for induction of the immune response. AIMS: The aim of this study was to determine immune response generated by the constructs in a mouse model and to understand the epitope specificities of the response. SETTINGS AND DESIGN: This was an observational study carried out in BALB/c mice. MATERIALS AND METHODS: The immunogenecity of Vgag construct was evaluated in BALB/c mice after multiple immunizations. T-cell response was monitored by the interferon-γ ELISPOT assay using HIV-1 C Gag overlapping peptides and anti-P24 antibodies were estimated by ELISA. STATISTICAL ANALYSIS USED: Graphpad prism software was used for statistical analysis and for plotting graphs. RESULTS: IFN-γ-secreting T cells and antibodies were detected against HIV Gag in mice after immunization. Although after repeated immunizations, antibody-mediated immune response increased or remained sustained, the magnitude of IFN-γ-secreting T cell was found to be decreased over time. The Gag peptides recognized by mice were mainly confined to the P24 region and had a considerable overlap with earlier reported immunodominant regions recognized by HIV-infected Indian patients. CONCLUSION: Vaccinia construct with a gag gene from transmitted HIV-1 virus was found to be immunogenic. The Gag regions identified by mice could have important implications in terms of future HIV vaccine designing.