HSV-1 amplicon vectors that direct the in situ production of foot-and-mouth disease virus antigens in mammalian cells can be used for genetic immunization

HSV-1 amplicon vectors encoding heterologous antigens were capable to mediate in situ generation of protein synthesis and to generate a specific immune response to the corresponding antigens. In this study, foot-and-mouth disease (FMD) virus antigens were used to generate a genetic vaccine prototype. The amplicons were designed to provide a high safety profile as they do not express any HSV-1 genes when packaged using a helper virus-free system, and they are able to encapsidate several copies of the transgene or allow the simultaneous expression of different genes. Virus-like particles were produced after cell processing of the delivered DNA. Inoculation of mice with 5 × 105 transducing units of amplicon vectors resulted in FMDV-specific humoral responses in the absence of adjuvants, which were dependent on the in situ de novo production of the vector-encoded antigens. Challenge of mice vaccinated with these amplicons with a high dose of live virus, resulted in partial protection, with a significant reduction of viremia. This work highlights the potential use of a HSV-1 amplicon vector platform for generation of safe genetic vaccines.