O1群霍乱弧菌PFGE分子分型和菌株流行能力关系研究

Association of PFGE with strains' epidemic capacity in Vibrio cholerae O1 serogroup isolates

目的调查福建省1962-2005年不同流行时期、不同流行血清群的O1群埃尔托型霍乱弧菌(EVC)的菌株间的遗传关联度和基因组的多态性;探讨不同PFGE型(簇)和霍乱菌株流行能力的关系。方法运用脉冲场凝胶电泳分子分型(PFGE)技术,对福建省1962-2005年代表性霍乱菌株进行分型,结合流行病学背景资料探讨不同PFGE型(簇)和相关霍乱菌株的流行能力。结果 77株霍乱菌株按100%的相似度分为61个PFGE型,按照90%的相似度可得到5个主要的PFGE簇,命名为G1-G5;52株小川型霍乱弧菌,按照100%的相似度分为47个PFGE型,按照90%的相似度可得到4个主要的PFGE簇[G1(o)-G4(o)];25株稻叶型霍乱弧菌按照100%的相似度分为15个PFGE型,按照90%的相似度,可得到2个主要的PFGE簇[G1(i)-G2(i)]。各个流行时期的菌株均有优势的PFGE簇,散发的菌株呈现分散的PFGE型,没有集中趋势。结论福建省3次流行的霍乱菌株有遗传关联性,在流行过程中产生基因变异出现新的优势PFGF簇;各地区间的霍乱流行有传播上的相关性。小川型G2(o)PFGE簇和稻叶型G1(i)PFGE簇的菌株有引起霍乱持续流行的能力,后者更有引发大规模病例数的能力。

During the past five decades, the emerging Vibrio cholerae strains have caused three major waves of epidemic in Fujian Province, China. In this study, in order to investigate genetic relationship and genomic diversity of representative iso- lates from historic cholera outbreaks in Fujian, pulsed fielded gel electrophoresis （PFGE） was performed for V. cholerae O1 se- rogroup E1 Tor biotype strains, the association of PFGE genotypes with strains~ epidemic capacity was further analyzed in com- bination with epidemiological information. According to 100% similarity, a total of 61 PFGE patterns were identified in 77 strains of O1 serogroup, however, five major pulsotypes （G1-G5） were designated based on 90% similarity. Among the 52 strains of Ogawa serotype, there were 47 PFGE patterns that could be classified into 4 pulsotypes [G1 （o）-G4（o）]. Mean- while, fifteen PFGE patterns were observed in another 25 strains of Inaba serotype, mainly clustered in 2 pulsotypes [GI（i）-G2 （i）]. Several predominant pulsotypes were determined in strains of diverse epidemic waves, however, sporadic isolates showed dispersed pulsotypes without clustering trends. Therefore, it is concluded from these data that genetic relationship was demon- strated among V. cholerae strains from three epidemic waves in Fujian, that novel predominant pulsotypes emerged in the process of epidemic when genetic variations occurred, and that there was geographic transmission association between cholera epidemics in prefectures. Particularly, this observation is also suggested that strains from pulsotype G2（o） of Ogawa serotypeand pulsotype G1 （i） of Inaba serotype are capable of causing persistent cholera, the latter is capable of inducing larger scale of disease burden.