鱼源气单胞菌的毒力基因检测、分型及致病力

为调查鱼源气单胞菌毒力基因与其致病力的相关性,以2009--2018年从不同患病鱼分离的173株气单胞菌为研究对象,通过检测毒力相关基因、测定溶血活性、腹腔注射感染异育银鲫等方法开展评价.通过管家基因gyrB分子鉴定结果显示,173株气单胞菌中维氏气单胞菌(119/173,68.9％)和嗜水气单胞菌(50/173,28...

Detection, genotyping and pathogenicity of virulence genes in Aeromonas species isolated from diseased freshwater fish

To investigate virulence genes and pathogenicity of Aeromonas species isolated from different diseased freshwater fish in 2009-2018,virulence genes including aer, act, fla, lip, gcaT, exu, ast, alt, eprCAI and ahyB were detected and the bacterial pathogenicity with different virulence genotype was assessed through intraperitoneal (IP) injection challenge Gibel carp. Molecular identification revealed that A.veronii (119/173, 68.8%) and A.hydrophila (50/173, 28.9%) were the most prevalent species in the diseased fish based on sequencing of gyrB. The distribution of 10 virulence factors including aer(162/173, 93.64%), act(131/173, 75.72%), ast(55/173, 31.79%), alt(58/173, 33.53%), lip(152/173, 87.86%), exu(154/173, 89.02%), fla(143/173, 82.66%), gcaT (148/173, 85.55%), eprCAI(41/173, 23.70%) and ahyB(51/173, 29.48%) were determined and 173 strains were sorted into 7 clusters and formed 53 genotypes according to the virulence distribution profile. The challenge tests showed that A.veronii isolates were generally less virulent than A.hydrophila isolates when infecting Gibel carp via IP injection. At the challenge dose of 3.0×10_⁶CFU per fish, A.hydrophila strains(16/20) were highly pathogenic and the mortality reached 90%-100%, but most A.veronii isolates (35/38)were less virulent or avirulent and only A.veronii YC170511, XZ180501 and GZ09007 with 5 ~ 7 virulence genes caused 80%-100% experimental fish death. The study suggested the pathogenicity of A.hydrophila isolates had obvious correlation with these virulence genes, but A.veronii isolates not. The research results have important reference significance for epidemiological investigations of motile aeromonad septicemia and vaccine research.