Long-term functional duration of immune responses to HCV NS3/4A induced by DNA vaccination

Abstract

We have investigated the ability of hepatitis C virus non-structural (NS) 3/4A-DNA-based vaccines to activate long-term cell-mediated immune responses in mice. Wild-type and synthetic codon optimized (co) NS3/4A DNA vaccines have previously been shown to be immunogenic in mice, rabbits and humans, although we have very poor knowledge about the longevity of the immune responses primed. We therefore analyzed the functionality of primed NS3/4A-specific immune responses in BALB/c (H-2d) and/or C57BL/6J (H-2b) mice 1, 2, 3, 4, 6, 12 and 16 months after the last immunization. Mice were immunized one, two, three or four times using gene gun delivery to the skin or by intramuscular administration. Immunological responses after immunization were monitored by protection against in vivo challenge of NS3/4A-expressing syngeneic tumor cells. In addition, functionality of the NS3/4A-specific T cells was analyzed by a standard cytotoxicity assay. First, we identified a new unique murine H-2d-restricted NS3/4A cytotoxic T lymphocyte (CTL) epitope, which enabled us to study the epitope-specific immune responses. Our results show that the coNS3/4A vaccine was highly immunogenic by determination of interferon-γ/tumor necrosis factor-α production and lytic cytotoxic T cells, which could efficiently inhibit in vivo tumor growth. Importantly, we showed that one to four monthly immunizations protected mice from tumor development when challenged up to 16 months after the last immunization. When determining the functionality of NS3/4A-specific T cells in vitro, we showed detectable lytic activity up to 12 months after the last immunization. Thus, NS3/4A-based DNA vaccines activate potent cellular immune responses that are present and function in both BALB/c and C57BL/6J mice up to 12–16 months after the last immunization. The induction of long-term immunity after NS3/4A DNA immunization has not been shown previously and supports the use of NS3/4A in hepatitis C virus vaccine compositions.

Listeriolysin O immunogenetic adjuvant enhanced potency of hepatitis C virus NS3 DNA vaccine

“…Guan et al showed that adenovector expressing truncated NS3 and core not only stimulate humoral immune response but also initiate strong cellular immunity against specific antigen; in addition, it provides a reasonable protective response . The current study revealed significant immune inducible effect and significant tumor growth inhibition of NS3 in mice model compared to control groups that may be due to immunodominat epitope in NS3 …”

“…34 The current study revealed significant immune inducible effect and significant tumor growth inhibition of NS3 in mice model compared to control groups that may be due to immunodominat epitope in NS3. 27,35,36 LLO contains four structural domains and all of these domains induce apoptosis through caspase dependent and independent mechanisms. 37 Because of its toxicity, it cannot be used thoroughly as an applicable adjuvant, and it is necessary to remove toxic domains.…”

Priming with two DNA vaccines expressing hepatitis C virus NS3 protein targeting dendritic cells elicits superior heterologous protective potential in mice

“…Recently, strategies for developing a therapeutic vaccine against HCV infection have focused on inducing T-cell responses to NS antigens [6,10,11,22,25,[33][34][35][36][37][38]. Ad vectors are also being employed in a phase I vaccine trial to deliver NS HCV proteins (NS3-5B) to 36 healthy Fig.…”

A targeted controlled force injection of genetic material in vivo

“…Production of IFN-γ and IL-2 cytokines was determined by a commercially available ELISpot assay (Mabtech, Nacka Strand, Sweden) as described previously. 23 The number of spots was counted using the AID iSpot reader and software version 7.0 (AID, Strassberg, Germany). The number of spots (cytokine-producing cells) was determined at each concentration of peptide or protein, and the results given as the number of IFN-γ or IL-2-producing cells per 10 6 cells.…”