Comparison of HCV Core and CoreE1E2 Virus-Like Particles Generated by Stably Transfected Leishmania tarentolae for the Stimulation of Th1 Immune Responses in Mice

Background: Virus-like particles (VLPs) could be improved into successful immunogens as well as a potent delivery vehicle, but however, the current expression systems for VLPs production have some limitations. Method: Recently, we developed a novel strategy to produce two HCV VLPs containing core or coreE1E2 proteins using stably transfected Leishmania tarentolae promastigotes. Then, BALB/c mice were injected by both viral like particles in different immunization strategies such as homologous DNA-, homologous VLP-, and heterologous DNA/ VLP-based immunizations. Results: TEM microscopy indicated HCV core and HCV coreE1E2 VLP assembly with average size of 30-40 and 40-60 nm after purification, respectively. Our results showed that homologous immunizations with both HCV core or coreE1E2 VLPs significantly induced anti-core or anti- coreE1E2 antibody responses, respectively as well as secretion of IFN-γ cytokine as compared to other strategies. Moreover, DNA-prime/VLP-boost regimens significantly elicited higher levels of IFN-γ and antibody responses in comparison with homologous DNA/DNA regimens. The groups immunized with homologous or heterologous coreE1E2 VLPs showed markedly higher immune responses as compared to groups immunized with core VLP regimens against coreE1E2 protein. Conclusion: The crude HCV VLPs generated by Leishmania expression system could elicit a Th1- type response as a promising vaccine candidate against HCV infections.