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志贺氏菌芳香族氨基酸合成酶基因缺陷能够使菌体明显减毒，并有可能成为新一代痢疾疫苗．用ＰＣＲ技术从野生型福氏２ａ志贺氏菌２４５７Ｔ中克隆出ａｒｏＡ基因，在体外进行精确的缺失突变，并通过体内同源重组，构建成△ａｒｏＡ突变体ＲＳ４２６．实验结果表明，这种突变体仍保持了侵袭能力和保护性Ｏ抗原的表达，但其毒力已明显降低，不能产生豚鼠角结膜炎，小鼠半数致死量明显提高．免疫保护试验显示，ＲＳ４２６可在小鼠中产生对福氏２ａ野生菌１００％的保护作用．
Shigella aromatic amino acid synthase gene defects can significantly attenuate the bacteria, and may become a new generation of diarrhea vaccine. The aroA gene was cloned from wild-type Shigella flexneri 2a 2457T by PCR, and the exact deletion mutation was performed in vitro. The aroA mutant RS426 was constructed by homologous recombination in vivo. The experimental results showed that the mutant still maintained the invasive ability and the protective O antigen expression, but its virulence has been significantly reduced, can not produce guinea pig keratoconjunctivitis, mice significantly increased the median lethal dose. Immunoprotection assays showed that RS426 produced 100% protection in wild-type P. recondarum in mice.