Effect Of Different Adjuvants On Immunogenicity Of Japanese Encephalitis Virus Inactivated Vaccine

Japanese encephalitis,which firstly found in Japan,is infected by Japanese Encephalitis Virus(JEV).It is a major cause of a zoonosis which leads to serval central nervous system infections in humans and abortion,testitis in pigs.In the case of lack of antiviral therapies,immunization is the most effective way to prevent JEV infection.To screen theadjuvant which can enhance the immunogenicity of inactivated vaccine against Japanese encephalitis,in this study,four different adjuvants were mixed with inactivated JEV respectively for preparing four different inactivated vaccines.Subsequently,the experiments of antibodies level of mice,challenge experiment and test of immune response of immunized mice were taken place.This study provided a scientific basis on the development of newly adjuvant inactivated JEV vaccines.1.Preparation of different adjuvant JEV inactivated vaccinesThe Japanese encephalitis virus SCYA201201 strain was continuously passaged on BHK-21 and inactivated with 0.2%formaldehyde for 24h.The inactivated virus solution was added to 603-nm adjuvant,Gel 01,ISA206 and IMS 1313 adjuvant respectively according to the instructions.These adjuvant inactivated vaccines were confirmed by safety test,the physicalproperties and sterile test after finished preparation.2.Antibody levels of different adjuvant JEV inactivated vaccinesFour kinds of inactivated vaccines were immunized with 3-week-old mice by intraperitoneal injection and the extra immunization was occurred a week after first immunization.Meanwhile commercial vaccines and PBS were considered as the control groups.The IgG antibody levels of inactivated vaccines were measured by ELISA2,4,6,8,10 weeks after first immunization respectively.The results indicated that all of the four inactivated vaccines and commercial inactivated vaccinecould stimulate the mice to produce antibodies,and the antibody levels were significantly different from the control group.The antibody level of Gel 01 adjuvant vaccine group was the highest among the four inactivated vaccines,and the antibody level of 603 nm adjuvant inactivated vaccine group was the lowest among the four inactivated vaccines.3.Immune response induced by different adjuvant JEV inactivated vaccinesMice were immunized with four inactivated vaccines respectively,and the proliferation of mouse spleen lymphocytes was subsequently detected with MTS assay.The levels of IL-2,IL-4 and INF-? cytokines in the supernatant and the IgGl and IgG2A of serum were detected by the kit.The results showed that all of the four inactivated vaccines could improve the levels of IL-2,IL-4,INF-?,IgG1 and IgG2A,and induce humoral immunity and cellular immune response in mice.Among them,JEV Gel 01 vaccine group had the best effect in stimulating humoral immunity and cellular immune response in mice.4.Immune challenge test of mice with different adjuvant JEV inactivated vaccineFour kinds of inactivated vaccines were immunized with 3-week-old mice by intraperitoneal injection and extra immunization was immunized after one week.JEV SC201301 strain was challenged by intraperitoneal injection one week after the second immunization.Theresults showed that the protective rates of ISA206 oil emulsion inactivated vaccine group,IMS 1313 oil emulsion inactivated vaccine,Gel 01 aqueous adjuvant inactivated vaccine and 603 nm adjuvant inactivated vaccine were 80%,70%,90%and 60%,respectively.The Gel 01 aqueous adjuvant inactivated vaccine was selected for the protection test of JEV gene type I strain YA1.The result showed the protect rate of Gel 01 aqueous adjuvant inactivated vaccine was 100%,indicating that the vaccine could be used for the protection of JEV gene type I virus infection.5.The safety experiment and the antibody level test of the optimistic adjuvant inactivated vaccinePiglets were immunized with Gel 01 aqueous adjuvant inactivated vaccine and the immunized swine were observed for the safety evaluation.Result showed that Gel 01 aqueous adjuvant inactivated vaccine is safe for swine.The antibody level induced by Gel 01 aqueous adjuvant inactivated vaccine was significantly increased and significantly different from HW1 commercial vaccine two weeks after immunization,which indicated Gel 01 aqueous adjuvant inactivated vaccine could induced high level of antibody against JEV.