Study of Japanese Encephalitis Virus(JEV) DNA Vaccines on Large Animals

Ping-Cheng Yang ； Yao-Horng Wang ； Mi-Hua Tao ； Chang-Jer Wu

《Journal of Genetics and Molecular Biology》 11卷2期 (2000/06) Pp. 84-84

https://doi.org/10.30047/JGMB.200006.0010

並列摘要

To date most of the studies on DNA vaccines has been performed on small laboratory animals, mostly in mice. However, in a number of cases, small experimental animals may not be good predicators of the situation that might occur in humans. To determine whether the JEV envelop SNA vaccine would be potentially efficacious in human clinical applications, pigs serve as an excellent model to investigate potential human vaccination protocols. First, the anatomy and physiology of skins between humans and pigs are similar. Second, the domestic pig represents an outbreed population and is relatively easy to house and handle. Third, pigs are natural hosts to JEV, and hence the DNA vaccines can be tested in a relevant natural virus-host system instead of in experimental model systems. The specific aims are : 1. To develop swine immunological assays; 2. To develop the JEV challenge model in swine; 3. To test the immunogenicity and protective efficacy of the JEV envelope DNA vaccine administered by intramuscular injection; 4. To test the immunogenicity and protective efficacy of the JEV envelope DNA vaccine administered by gene gun. Based on the above aims, we concluded that the challenging model should be set with a dose of 1x106 PFU/ml JEV for pigs. In viremia study, the virus titer of JEV in pigs peaked during 3 to 5 days post-challenge. In order to understand the potential effect of different anticoagulants on JEV titers during virus isolation, blood samples from the same pig were allocated into those tubes containing different anticoagulants suck as Sodium Heparin, Sodium Citrate, and EDTA.A group of blank tubes without anticoagulant was served as control. The results indicated that all kinds of anticoagulants do show inhibition on JEV titers during isolation. The best virus yield was in those tubes containing porcine blood samples without anticoagulants. In the test of optimal conditions of vaccination by gene gun, we compared different administration pressure including 400, 500, and 600 psi on the neck, abdominal, and groin skin with pGEP and pluciferase. After 3 days of vaccination, we checked location of pGEP and quantified the expression of pluciferase in skin samples. The 500 psi per shot on the neck was appropriate and most convenient to apply in pigs.