Zhao K, Duan X, Hao L, Wang X, Wang Y

J Microbiol Biotechnol. 2017 Oct 25. doi: 10.4014/jmb.1708.08017

Abstract

Newcastle disease (ND) is a serious infectious disease in poultry industry. The commercial vaccines can only offer a limited protection and some of them cost high and need adjuvants. At present, DNA vaccines have been widely used. However, the immune responses induced by DNA vaccines are too slow and low. Here, we constructed the transfer vectors with a different number of C3d as a molecular adjuvant (n=1, 2, 4, 6), and the vector was cloned into the optimal eukaryotic expression plasmid (pVAXⅠ-optiF) that expressed the F gene of NDV, which were named pVAXⅠ-F(o)-C3d1, pVAXⅠ -F(o)-C3d2, pVAXⅠ-F(o)-C3d4 and pVAXⅠ-F(o)-C3d6, respectively. Cell transfection test indicated that the pVAXⅠ-F(o)-C3d6 showed the highest expression. In vivo immunization showed that the chickens immunized with the pVAXⅠ-F(o)-C3d6 i.m. induced better immune responses than the chickens immunized with other plasmids. The protective efficacy of pVAXⅠ-F(o)-C3d6 i.m. was 80 % after challenge with the highly virulent NDV strain F48E9. The results in this study showed that the C3d6 can be used as a molecular adjuvant which quickly induced effective immune response and the pVAXⅠ-F(o)-C3d6 can be used as an effective vaccine to control NDV.