嗜水气单胞菌毒力与毒力基因分布的相关性

采用PCR扩增的方法对9株鱼源嗜水气单胞菌AEROM ONAS HYDROPHILA中的气溶素基因(AERA)、溶血素基因(HLYA)和丝氨酸蛋白酶基因(AHPA)进行了扩增。结果表明,6/9的A.HYDROPHILA中存在AERA基因,8/9的A.HYDROPHILA中存在HLYA基因,而在7/9的A.HYDROPHILA中检测到AHPA基因。通过比较基因检测的结果与嗜水气单胞菌对鲫鱼的致病性,发现AHPA阴性菌株是无毒株,强毒株都呈AERA HLYA AHPA 基因型。AERA HLYA AHPA 基因型是致病性嗜水气单胞菌主要的基因型。本研究首次发现AHPA阳性的嗜水气单胞菌皆为毒力菌株,并且发现AERA和AHPA基因存在相关性,探讨了嗜水气单胞菌致病性与毒力基因分布的关系。

The Correlation Between the Distribution Pattern of Virulence Genes and the Virulence of Aeromonas hydrophila Strains

Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin and extracellular serine protease(i.e.aerA,hlyA and ahpA,respectively).These genes were investigated using polymerase chain reaction(PCR) with specific primers for each gene.And the pathogenicities to Carrassius auratus ibebio of these strains were also assayed.PCR results demonstrated that the distribution patterns of aerA,hlyA and ahpA were different in these strains.6/9 of A.hydrophila strains were aerA positive,8/9 of strains were hlyA positive,whereas,7/9 of strains were ahpA positive.However,the assay for pathogenesis found that two strains(Aeromonas hydrophila XS91-4-1 and C2) were strong virulent,two strains(Aeromonas hydrophila ST78-3-3 and 58-20-9) avirulent and the rest middle virulent to the fish.In conclusion,there are significant correlation between the distribution pattern of the three virulence genes and the pathogenicity to Carrassius auratus ibebio.All strong virulent A.hydrophila strains were aerA~ hlyA~ ahpA~ genotype,and all aerA~ hlyA~ ahpA~ strains were virulent.Strains with the genotype of aerA-hlyA-ahpA~ had middle pathogenicity.In the present study,we found for the first time that all A.hydrophila isolates with the ahpA positive were virulent to Carrassius auratus ibebio.Additionally,there was a positive correlation between the virulence of A.hydrophila and the presence of aerA and ahpA.