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.