鼠伤寒沙门菌SL1344株ΔcrpΔasd缺失株的构建及生物学特性初步研究

Construction and characterization of a Salmonella typhimuriumSL1344ΔcrpΔasd mutant strain

构建鼠伤寒沙门菌SL1344ΔcrpΔasd双基因缺失突变株,并对其生物学特性进行初步研究。首先以χ7213(pREΔasd)为供体菌,SL1344Δcrp为受体菌进行结合转移,通过自杀性质粒介导的等位交换技术两步法筛选SL1344的ΔcrpΔasd双缺失株。该缺失株在有外源DAP的存在下能够正常生长,且能稳定遗传缺失的asd基因;其血清型与亲本株SL1344Δcrp及强毒株SL1344保持一致;其生化特性与亲本株基本相同,但与强毒株相比变化较明显,且生长速度明显减慢;雏鸡毒力试验结果表明其毒力较SL1344降低约105倍。鼠伤寒沙门菌SL1344ΔcrpΔasd缺失株构建成功,为进一步开发以鼠伤寒沙门菌为载体的口服疫苗奠定了基础。

Construction and identification of Salmonella typhimurium SL134△ mutant strain （SL134△AcrpAasd） ,and the phenotype of SL134△△crpAasd mutant was analyzed preliminarily. Firstly,E. coli donor strain Z7213（pREAasd） was conjugated with SL134△Acrp,the recipient. The SL1344△crpAasd mutant was constructed through the two-step method introduced by the transduction of recombinant suicide plasmid. It indicated that AcrpAasd mutant can grow normal- ly when foreign DAP was supplied,and it was stabile with the recombinant Aasd gene in vitro ,the O and H antigens were identical to SL1344△crp and 8L1344 strain. The fermentation patterns and growth rate of the mutant were different from SL134△ strain,obviously,and the growth velocity of the mutant was more slow. The virulence of SL134△AcrpAasd mutant strain was 105 times lower than SL134△ strain. The SL134△AcrpAasd mutant was constructed successfully. It is con siderable that this AcrpAasd mutant could be a potential oral vaccine vector to express foreign an- tigen or act as a eukaruotic expression plasmid carrier.