志贺氏菌芳香族氨基酸缺陷减毒株的构建

目的构建一种新型痢疾疫苗，使其较完整地保留保护性抗原，又不致丧失其侵袭力。方法用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ΔaroA突变体RS426。结果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。结论免疫保护试验显示，RS426可在小鼠中产生对福氏2a野生菌100％的保护作用。

Construction of an aromatic amino acid attenuated strain

Objective Shigella spp "an ic appropriately attenuated by the ~ gene mutation. Method The ~ mutant may beused as a new generation canclidate anti -- shigella vaccine. The areA gene of S. flexneri 2 a 2457 T was alnphoed by aiR and mutatedby Pnyise deletion of a driddle 4'f fragment of the ~A gene in vial. The constrUcted boA gene was ugh to replace the wild -- acamA gene of S. fie~ri 2 a 2457T I) honlologous recolnbination which resulted in the constrUction of a algA mutant RS 426. RedtSExperimental results showed that illis strain retained the ability of cell invasion and 0 antigen expression, but ho adn st~canily attenuated, Conclndon That is codrirmed h}' iEs loss of the ability' to provoke the keratoconjunctivitis in tinea -- pig and much higherLDro value in face.