ABSTRACT
Development of a vaccine targeting human immunodeficiency virus-1 subtype C (HIV-1C) is an important public health priority in regions with a high prevalence of the clade C virus. The present study demonstrates the immunogenicity of recombinant Semliki Forest virus (SFV)-based virus-like replicon particles (VRPs) expressing Indian HIV-1C env/gag/polRT genes. Immunization of mice with recombinant VRPs in a homologous prime-boost protocol, either individually or in combination, elicited significant antigen-specific IFN-γ T cell responses as detected by the ELISPOT assay. Additionally, Gag-specific TNF-α secreting CD8+ and CD4+ T cells and Env-specific IL-2 secreting T cells were also elicited by mice immunized with Gag and Env constructs, respectively, as estimated by intracellular cytokine staining assay. Moreover, an HIV Pol-specific TNF-α response was elicited in mice immunized with a combination of the three VRP constructs. Furthermore, HIV-1C Gag and Env-specific binding antibodies were elicited as verified by gp120 ELISA and p24 Gag ELISA, respectively. The immunogenicity of VRPs was found to be higher as compared to that of RNA replicons and VRPs may therefore be promising preventive and therapeutic candidate vaccines for the control and management of HIV/AIDS.
Subject(s)
AIDS Vaccines/immunology , HIV Infections/immunology , HIV-1/immunology , Semliki forest virus/physiology , Virion/immunology , AIDS Vaccines/genetics , Animals , Female , Fusion Proteins, gag-pol/genetics , Gene Products, env/genetics , Genetic Vectors , HIV Antibodies/blood , HIV Antigens/genetics , Humans , Mice , Replicon/genetics , Vaccination , Vaccines, DNAABSTRACT
Development of recombinant vaccines is considered as a promising approach to prevent transmission and eradication of HIV/AIDS. Candidate vaccines tested so far have shown poor to modest efficacy. Self-amplifying RNAs of positive strand alphaviruses are reported to be promising vectors for development of recombinant vaccines. This study describes the construction, in vitro expression and in vivo immunogenicity of recombinant RNA vaccines developed by individually cloning gag, env and polRT genes of primary HIV-1C Indian isolates using Semliki Forest virus (SFV) vector. HIV-1C specific T cell responses were detected in mice immunized with rSFV2gen/gag RNA by IFN-γ ELISPOT assay. Furthermore, using flow cytometry based intracellular cytokine staining (ICCS) assay HIV-1C specific IL-2 responses were detected in immunized mice that were mediated by both CD4(+) and CD8(+) T cells. Mice immunized with rSFV2gen/env RNA elicited HIV-1C Env-specific antibodies as detected by gp120 ELISA. The Env, Gag and Pol (RT) RNA constructs in combination elicited better HIV-1C Env-specific humoral responses compared to mice immunized with Env RNA alone. In conclusion, rSFV2gen RNA constructs encoding HIV-1C antigens elicited clear cell mediated and humoral immune responses in mice, thus demonstrating the potential of self-amplifying rSFV2gen RNA as a promising candidate for anti-HIV vaccine development.
