Immune responses and protective effects against Japanese encephalitis induced by a DNA vaccine encoding the prM/E proteins of the attenuated SA14-14-2 strain.

Japanese encephalitis virus (JEV) is the causal pathogen of Japanese encephalitis (JE), which has become a severe public health problem and is one of the most rapidly spreading mosquito-borne diseases worldwide. Currently, there is no specific treatment for JEV. A vaccine would be an effective measure for reducing morbidity and mortality. Although the live attenuated vaccine SA14-14-2 has been approved in some countries, it is still necessary to develop safer, more effective, and less costly vaccines. In this study, a DNA vaccine candidate, pV-SA14ME, expressing the prM/E proteins of SA14-14-2 was inoculated into BALB/c mice via intramuscular electroporation, and the immunogenicity and degree of protection were evaluated. We found that administration of 50 μg pV-SA14ME via electroporation via three immunizations could induce persistent humoral and cellular immune responses and effectively protect mice against lethal JEV challenge. This study provides a basis for the subsequent promotion and use of the vaccine and lays the foundation for its further use in swine and humans.