| To construct an attenuated live vaccine candidate for Japanese encephalitis (JE)/Zika chimeric virus and to assess its safety and immune protection effects. The prM/E genes of Zika virus strains FSS13025 and PRVABC59 were respectively replaced into the corresponding regions of the JE vaccine strain to construct full-length infectious clones of the JE/Zika chimeric virus. Viral RNA was transcribed in vitro, and electroporated into BHK-21 cells to rescue the two chimeric viruses, ChimZIKV(13025) and ChimZIKV(59). Results from restriction enzyme digestion, immunofluorescence, and sequencing showed that the infectious clones were correctly constructed, and the chimeric viruses were successfully rescued. Plaque assays indicated that the plaque diameters of the chimeric viruses were smaller compared to the parental strains (P<0.01). Growth curves showed that the chimeric viruses proliferated less efficiently in BHK-21 and C6/36 cells compared to the JE vaccine strain. Cytotoxicity assays revealed that the chimeric viruses exhibited lower toxicity to passage cells compared to the JE vaccine strain (P<0.01). In mice, the chimeric viruses exhibited low neuroinvasiveness and higher neurovirulence in the brain. Immunization of mice with ChimZIKV(13025) and ChimZIKV(59) induced higher neutralizing antibody titers. After immunizing female mice, the protection rates of newborn suckling mice against the wild-type Zika virus strain PRVABC59 were 95% and 89%, respectively, with no detectable viremia in the suckling mice. The results of this study indicate that the chimeric viruses ChimZIKV(13025) and ChimZIKV(59) possess good immunogenicity, low neuroinvasiveness, and provide strong protection to newborn suckling mice following immunization with the chimeric viruses. However, the chimeric viruses still exhibit some degree of neurovirulence in the mouse brain. |
