1.Identification of 2 strains of suspected Yersinia pestis isolated from Marmot,,himalayana in Dege County,Sichuan Province
Zhi-zhen, QI ; Dan-ba, LUOZHI ; Yong-jun, DUAN ; Min, LI ; Bai-zhong, CUI ; Rui-xia, DAI ; Jian-ping, FENG ; Cun-xiang, LI ; Shou-hong, YU ; Zu-yun, WANG ; Hu, WANG ; Xing, JIN ; Hai-hong, ZHAO ; You-quan, XIN ; Ling-ling, REN ; Qing-wen, ZHANG ; Rong-jie, WEI ; Li-xia, JIN ; Yong, JIG ; Hao-ming, XIONG ; Xiao-lin, LUO ; Sang-zhu, ZEREN ; Hong, WANG ; Shan-hu, ZHANG ; Wen-tao, GUO ; Xue, WANG ; Ze-li, DANBA ; Dan, WENG ; Dai-li, WANG
Chinese Journal of Endemiology 2009;28(1):48-53
Objective Throush identify biochemical characteristics and virulence factors of 2 strains suspected Yersinia pestis(Y.pestis)isolated from the dead Marmota himalayana(M.himalayana)to confirm the nature epidemic focus in Dege County,Sichuan Province.Methods Y.pestis was analyzed by specific staining and shape,culturing characteristics,splitting-test by bacteriophage,test of biochemical characteristics and glycolysis ability,virulence factors,virulence,nutritional requirement,plasmid,genetic test and genetic type. Results The tested strains were Gram staining bacilus.The main biochemical characteristics were Arabinose(+)、 Rhamnose(-),Maltose(+),Melibiose(-),Glycerol(+),Denitrification(+).The virulence factors with FI+.VW+, Pgm+,Pst I+;and with the common 6.0×106,45.0×106,65.0×106 plasmids,also with the virulence-relative plasmid gene.Both their absolutely lethal dose(LD100)in mice were 50 bacteria.The nutritional requirement appeared which were depended on Phenylalanine and Methionine.With the Genomovar 5 genotype characteristics of M.himalayana plague foci of Qinghai-Tibet plateau.The difference between tested strains and Yersinia pseudotubercuosis on the 3 different culture medium was obvious.The tested strains had a Y.pestis' specific 3a fragment,Pst I and FI-Ag,at 22 ℃,the strains could be split by bacteriophage completely.Conclusions According to the diagnostic criteria of plague in China,the 2 suspected strains isolated from Dege County,Sichuan Province ale confirmed as Y.pestis.both with powerful virulenceand with the characteristics of the Y.pestis of M.himahtyana in Qinghai-Tibet plateau plague natural focus.
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