[Analysis of characteristics of major pathogenicity-related genes of Vibrio cholerae isolated in Guangzhou area from 2001 to 2005].
OBJECTIVE
To apply multiplex polymerase chain reaction (MPCR) assay and sequencing in study of the carrying status of four pathogenicity-related genes of Vibrio cholerae (V.cholerae) and the variation of ctxA.


METHODS
Primers targeting cholera toxin sub-unit A gene (ctxA), toxin-coregulated pilus gene (tcpA), accessory cholera enterotoxin gene (ace), zonula occludens toxin gene (zot) were designed and the MPCR method was applied to detect the pathogenicity-related genes of 276 strains of V.cholerae isolates. The amplified fragments of ctxA gene were sequenced and the genetic homology of the amplified fragments of ctxA was analyzed.


RESULTS
Of the 276 strains of V.cholerae, 93.9% strains from human sources belong to the pathogenicity-related genes type A (ctxA(+)tcpA(+)ace(+)zot(+) type) and 6.1% belong to pathogenicity-related genes type C (ctxA(-)tcpA(-)ace(-)zot(-) type). Type A strains from clinical sources were isolated from patients with mild to severe symptom and carriers, among which 68.5% were isolated from patients with mild symptom and 21.9% from carriers. All 63.6% of type C strains from clinical sources were isolated from patients with mild symptom and 36.4% from carriers. The proportion of type C strains that caused mild symptom was higher than that of type A strains. Of the 78 strains isolated from the environment, 9.0% strains belong to pathogenicity-related type A and 35.9% belong to the pathogenicity-related genes type B (ctxA(-)tcpA(-)ace(+)zot(+) type), while 55.1% belong to pathogenicity-related genes type C. The sequencing results showed little genetic variation among the amplified fragments for ctxA.


CONCLUSIONS
MPCR disclosed the polymorphic status of pathogenicity-related gene patterns in V.cholerae isolates of Guangzhou, providing effective means for further study on evolution of pathogenicity-related genes among V.cholerae isolates from human and environmental sources. This study also offers significant guidance for effective prevention, control and warning against cholera epidemic in local area.
Wang
Ming
M
Guangzhou Center for Disease Control and Prevention, Guangzhou, 510080, China. wangming@gzcdc.org.cn
Li
Xiao-quan
XQ
Mo
Zi-yao
ZY
Liu
Yu-fei
YF
Deng
Zhi-ai
ZA
Shen
Ji-chuan
JC
Zhang
Xin-qiang
XQ
D002681:China; D002772:Cholera Toxin / Q000235:genetics*; D004269:DNA, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction; D017421:Sequence Analysis; D014734:Vibrio cholerae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
D004269:DNA, Bacterial; D002772:Cholera Toxin