Abstract：In this paper a gene vaccine C1-△CLIP-Ii-F343 containing Newcastle disease virus(NDV) F epitope based on chicken invariant chain(Ii) as carrier and its immune response in mice are studied. First the NDV-F epitope gene vaccine, an endogenous targeting fragment, was constructed by overlap extension method via three cycles of PCR, in which class-Ⅱ associated invariant chain peptide (CLIP) of chicken Ii was substituted with NDV F epitope, F343 (327-359 AA). Secondly the transfection of COS7 cells with C1-△CLIP-Ii-F343 and C1-F343 (no Ii carrier) was observed. And both could efficiently express in the cost cells. Finally twenty-five female Balb/c mice(Mus musculus) of 6~8 weeks old were randomly divided into five groups and injected with C1-△CLIP-Ii-F343 and C1-F343, as experimental controls with C1-△CLIP-Ii, pEGFP-C1 and saline, respectively. After immunizations three times, the humoral immune response was estimated. The C1-△CLIP-Ii-F343 and C1-F343 could induce the mice to produce specific antibody to NDV-F and the titers could reach 1/6400 and 1/1600, respectively. Western blot results showed that the antibodies could bind specifically with NDV allantoic fluid of chicken embryo injected with NDV and PET-NDV-F306 protein of prokaryotic expression. The results suggest that the C1-△CLIP-Ii-F343 epitope vaccine based on Ii as carrier can stimulate specific humoral immune response in mice and it may be a potential candidate gene for NDV vaccine development.
