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目的 研究多重耐药伤寒沙门菌耐药质粒pRST98是否具有沙门菌属中其他致病菌毒力质粒上的高度保守基因——spv,并对扩增的spv基因进行克隆及核酸序列测定。方法 对已确定能增强细菌毒力表型的耐药质粒pRST98,用spv基因特异引物进行PCR扩增和SPV探针的Southerblot分析,并将扩增到的spv基因片段装入克隆载体pGEM TEASY进行测序。结果 PCR和Southernblot结果显示,伤寒沙门菌耐药质粒pRST98上亦存在spv基因的同源序列spvR和spvB,其ORF分别为894bp和1 776bp,与鼠伤寒沙门菌毒力质粒上spv基因的同源性超过99%。结论 本研究从核酸水平首次证实伤寒沙门菌耐药质粒pRST98具有多效性,是既编码细菌抗药性又编码细菌毒力的“嵌合型”质粒。
Objective To study whether the multi-drug resistant Salmonella typhi resistance plasmid pRST98 has the highly conserved gene spsp in virulent plasmids of other pathogens in Salmonella, and cloned and sequenced the amplified spv gene. Methods The resistant plasmid pRST98, which has been confirmed to enhance the virulence phenotype of bacteria, was amplified by PCR using spv-specific primers and Southerblot analysis by SPV probe. The amplified spv gene fragment was inserted into the cloning vector pGEM TEASY Sequencing. Results The results of PCR and Southern blot showed that spv gene spvR and spvB were also found in Salmonella typhimurium resistant plasmid pRST98 with ORFs of 894 bp and 1 776 bp, respectively, which were homologous to the spv gene of Salmonella typhimurium virulence plasmid Sex more than 99%. Conclusion This study demonstrated for the first time that the plasmid pRST98, a Salmonella typhi resistance plasmid, has pleiotropic effects at the nucleic acid level and is a “chimeric” plasmid that encodes bacterial resistance as well as bacterial virulence.