Immunogenicity Of Nipah Encephalitis Virus Glycoprotein And Fusion Protein DNA Vaccines In Mice

Nipah encephalitis is a deadly zoonotic disease caused by Nipah virus (NiV). NiV has a wide rangeof hosts. Pig is an amplifying host of NiV. Nipah encephalitis had broken out in Malaysia, India,Bangladesh and Singapore mainly in southeast Asia regions. NiV outbreak brought serious threat tohuman and animal health and results in great losses in the relative countries. At present there is noeffective treatment for the disease, thus vaccination is considered to be very important for the NiVcontrol and prevention. Nipah encephalitis has not occurred in China so far, however, because of thegeographical location, the prosperity of international trade, and especially the serological evidenceof NiV antibodies was detected in the bats in some southern provinces of China, the development ofNiV vaccines is highly necessary and urgent in our country. In this study, the immunogenicity of DNAvaccines encoding NiV G and F pritein (designated as pCAGG-NiVG and pCAGG-NiVF) wasevaluated in mice. The IgG levels after priming and boosting were detected by ELISA. The neutralizingantibodies were detected by Vesicular Stomatitis Virus (VSV) membrane enveloped NiV G andF protein psudotyped virus based neutralization assay. pCAGG-NiVF induced specific CD8+T cellsresponse was measured by FCM and ELISPOT. ELISA results showed specific IgG antibody level ofthe immunized mice after priming and boosting was significantly higher than the control grou（pp<0.05）.The IgG level increased significantly after the second dose (P<0.05). pCAGG-NiVG and pCAGG-NiVFinduced similar level of NiV neutralizing antibodies after priming, although the levels were not high;while after the second dose the neutralizing antibodies were boosted significantly(P<0.05). In order toevaluate the cellular response, a NiV F protein CD8+T cell epitopte was used to stimulate the spleencells of the pCAGG-NiVF immunized mice, the percentage of the activated CD8+T cellswere determined by FCM and ELISPOT assay. The results indicated pCAGG-NiVF could inducespecific CD8+T cell responses after the first dose and the responses were greatly boosted after thesecond dose (p<0.05). This study indicated pCAGG-NiVG and pCAGG-NiVF induce both NiV specificneutralizing antibodies and CD8+T cell responses in mice,thus appear to be potential Nipah vaccinecandidates in future.