Novel AAV-based genetic vaccines encoding truncated dengue virus envelope proteins elicit humoral immune responses in mice.

The envelope protein of dengue virus is involved in host cell attachment for entry and induction of protective immunity. Current efforts are focused on producing a tetravalent vaccine by mixing four monovalent vaccine components. In this work, we developed a genetic vaccine based on a novel adeno-associated viral (AAV) vector expressing the carboxy-terminal truncated envelope protein (79E) of dengue virus. The expression of the recombinant 79E protein in HEK 293 cells was confirmed by Western blot. Vectors packaged with novel AAV capsids (AAV2/8 or AAV2/rh32.33) were injected into C57BL/6 mice intramuscularly. Dengue virus antigen was produced in the mice and induced long-lasting antibody responses against the dengue virus still detectable 20 weeks after immunization. AAV2/8 vaccine induced higher anti-dengue virus antibody levels than AAV2/rh32.33 vaccine or AAV plasmid. Furthermore, the anti-dengue antibodies could neutralize homogeneous dengue virus. These results demonstrated that the AAV vaccines possessed appropriate immunogenicity and could be used for the development of an effective dengue vaccine.