黄沙鳖白底板病病原菌的分离鉴定及6种毒力基因检测

CHARACTERIZATION OF WHITE PLASTRON DISEASE PATHOGENS AND DETECTION OF SIX KNOWN VIRULENCE GENES IN TRUOGX SINENSIS

用常规方法从患典型白底板病黄沙鳖的心脏、肝脏等处进行细菌的接种分离,通过人工感染确定分离菌株的致病性,API 20NE、16S rRNA基因序列分析进行病原菌鉴定和确定其系统发育地位,K-B纸片扩散法进行药敏试验,PCR检测病原菌的6种毒力基因。试验结果,共分离到13株病原菌,其中嗜水气单胞菌9株,温和气单胞菌4株。在9株嗜水气单胞菌中,有5株与Aeromonas hydrophila ATCC 7966菌株亲源关系最近,4株与Aeromonas hydrophila北京株QDC01的亲源关系最近;而4株温和气单胞菌与Aeromonas sobria ATCC43979的亲源关系最近。药敏试验结果,仅头孢哌酮对13株病原菌都高度敏感,来源于不同养殖区域的病原菌药敏结果相差较大。6种毒力基因的阳性率,Aer、Act和ahp均为100%,hly和Alt为92.31%,ahal为76.92%;毒力基因型共有4种,嗜水气单胞菌主要为hly+Aer+Alt+Act+ahal+ahp+基因型,而温和气单胞菌主要为hly+Aer+Alt-Act+ahal+ahp+基因型,同时携带hly基因的菌株其致病力更强。

Pathogenetic bacteria were isolated from hearts and livers of the infected individual Truogx sinensis, cultured on conventional methods, and used as challenge to determine their infectiveness. Identities of the isolated pathogens were distinguished through API 20NE, their phylogenetic status were analyzed by 16S rRNA sequencing and their sen- sitivities to drugs were tested by K-B method. The six known virulence genes in the pathogens were detected by PCR. The results showed that, of the thirteen pathogens abtained, nine strains were Aerornonas hydrophila, and four strains were Aeromonas sobria. In phylogenetical relationship of the nine Aeromonas hydrophila, five strains were close to Aeromonas hydrophila ATCC 7966, and four strains were close to Aeromonas hydrophila QDC01, while four Aeromo- has sobria were close to Aerornonas sobria ATCC 43979. Drug sesnsitive testes indicated that only thirteen strains were found to be highly sensitive to cefoperazone, and pathogens from different farms presented to be quite different in drug sensitivity. Virulence gene detection showed that Aer, Act and ahp was positive at 100%; hly and Alt, 92.31%; and A hal, 76.92%. Four genotypes were found in pathogens isolated, being hZy^＋Aer^＋Alt^＋Act^＋ahal^＋ahp^＋ and hly^＋Aer^＋Alt-Act^＋ahal^＋ahp^＋, mainly dominating in Aeromonas hydrophila and Aeromonas sobria, respectively, and strains with hly exhibited stronger pathogenicity.