Biochemical and virulence determination of yersinia pestis in Qinghe county of Altay mountain,Xinjiang
Objective To understand the biochemical phenotype of Yersinia pestis strains and the pathogenicity to Kunming mice from Altay mountain,Xinjiang.Methods There were 5 strains of yersinia pestis isolated from the mountain in Qinghe county of Altay prefecture,and 2 strains of Yersinia pestis isolated from north Tianshan gray marmot-long-tailed ground squired plague foci.The Yersinia pestis strains were tested by sugar and alcohol hydrolysis for identifying the biochemical phenotypes.Four strains of Yersinia pestis from the mountain in Qinghe county,and 2 strains of Yersinia pestis from north Tianshan gray marmot-long-tailed ground squired plague foci were selected for virulence test in Kunming mice to determine the virulence of the plague strains.Results The glycerol fermentation,nitration and denitrification were positive in the 5 strains of Yersinia pestis from Qinghe county.The biochemical determination showed classical type,without the capacity of catabolize rhamnose.Half lethal dose was 7.9 bacteria in 4 strains of plague from the mountain in Qinghe county.The minimum lethal dose of mice was less than 10 bacteria,and the strains were highly virulent strains of plague.Conclusions The biochemical determination of the Yersinia pestis strains from the mountain in Qinghe county of Altay shows classical type,and the strains are the strains with high virulence.