减毒沙门氏菌为载体在Vero细胞中表达传染性法氏囊病病毒多聚蛋白基因

用长距离RT-PCR扩增了传染性法氏囊病病毒（infectious bursal disease virus, IBDV）ZJ2000株多聚蛋白基因，定向克隆入真核表达载体Pci，电转化dam^-和phoP^－双突变的减毒鼠伤寒沙门氏菌ZJ111株，并直接转染Vero细胞。RT-PCR和间接免疫荧光试验可从Vero细胞中检测到阳性信号，SDS-PAGE和West blotting均可检测到41kD的蛋白条带。结果表明减毒沙门氏菌可将外源基因导入Vero细胞，并进行转录和表达，具有免疫反应性，为进一步研制减毒沙门氏菌为载体的IBDV口服DNA疫苗打下基础。

Expression of the Infectious Bursal Disease Virus Polyprotein in Vero Cells Using Attenuated Salmonella typhimurium as Transgenic Carrier

To examine if polyprotein gene(VP2/VP4/VP3) of Infectious Bursal Disease Virus (IBDV) could be delivered into mammalian cells and expressed using attenuated Salmonella typhimurium as vector. The IBDV polyprotein gene was amplified by RT-PCR and inserted in to pCI, an eukaryotic expression plasmid. The resulting recombinant pCI-VP2/VP4/VP3 was transformed by electroporation into attenuated Salmonella typhimurium strain ZJ111 (dam - and phoP -), which was then use to transfect the Vero cells. Gene specific RT-PCR revealed that VP2/VP4/VP3 was transcribed into mRNA in the Vero cells. Indirect immunofluorscence assay, SDS-PAGE and Western-blot analysis showed that VP2/VP4/VP3 was expressed and the product was immuno-reactive with anti-IBDV serum. This work provides essential precondition for developing a new oral DNA vaccine against IBDV.