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将控制伤寒杆菌Vi多糖抗原表达的ViaB基因片段亚克隆到表达载体pYA248上,构建成质粒SMM202并将SMM202引入到减毒鼠伤寒杆菌△Cya△crp突变株x4072中去,使x4072稳定地表达Vi抗原。表达Vi抗原的x4072菌株Vi4072仍具有通过胃肠道感染Balb/c小鼠的小肠、肠系膜淋巴结、脾和肝的能力。动物实验证明,小鼠经口服免疫Vi4072活菌后,可产生针对Vi抗原的血清抗体,分泌抗体和DTH反应;经Vi4072口服免疫后的小鼠产生了对伤寒杆菌和鼠伤寒杆菌强毒株攻击的抵抗力。
The ViaB gene fragment controlling the expression of the Viam polysaccharide antigen of Salmonella typhi was subcloned into the expression vector pYA248 to construct the plasmid SMM202 and the SMM202 was introduced into the attenuated Salmonella typhimurium △ Cya △ crp mutant x4072 to stably express x4072 Vi antigen. The Vi4072 strain Vi4072 that expresses the Vi antigen still possesses the ability to infect the small intestine, mesenteric lymph nodes, spleen and liver of Balb / c mice via the gastrointestinal tract. Animal experiments show that the mice via oral administration of Vi4072 live bacteria, can produce anti-Vi antibodies for serum antibodies, secreted antibodies and DTH response; oral administration of Vi4072 mice produced Typhimurium and Salmonella typhimurium strains of virulent attacks Resistance.