Liposome-based HCV vaccine enhances protective cellular immunity and IFN-gamma secretion in mice
Abstract:
HCV is a worldwide health problem and with the lack of effective treatment, vaccination becomes an urgent task, especially in developing countries. The effective vaccine should elicit long-lasting antibodies but most importantly induce a vigorous, multi-specific cellular immune response that includes both helper and cytotoxic T lymphocytes. Advances in liposome technology account for much of the progress in vaccine delivery systems. Therefore, this study aimed at investigating the potential immunogenicity of HCV core antigen, and assessing the influence of the novel antigen carried on liposomes on T cell proliferation and IFN-gamma production as potent markers of cellular immune response. Several formulations for immunization were prepared, including liposomal encapsulation of the Ag. The study was conducted on a total of 95 female inbred (C57B1/6J) mice divided into five groups including a control group. Spleen lymphocytes were evaluated for cellular proliferation using 3-(4, 5-Dimethylthiazol-2-YI)-2, 5-Diphenyltetrazolium Bromide (MTT) assay and for secretion of IFN-gamma by ELISA. Mice injected with liposomes carrying HCV core Ag (group 1) showed a highly significant increase in splenocytes proliferation (spontaneously and after stimulation with the Ag) compared to all other groups, with a stimulation index (S.I) of 1.47 (P < 0.001). The second highest cellular proliferation was noticed in mice injected with core Ag and CFA (group 2) (S.I = 1.29) with a significant difference from group I (P = 0.001). Mice injected with core Ag alone showed a non-significant difference from the control group (P = 0.126). IFN-gamma level was the highest in liposomal Ag group with a highly significant difference; both spontaneously (56.3 pg/L) and with stimulation (68.32) (P < 0.001) followed by mice injected with core Ag with CFA. In conclusion, Liposomal formulation of HCV peptide vaccine is effective as direct in vivo antigen loading and activation of T cells leading to protective HCV antiviral responses.
