关键词: 嗜水气单胞菌, 分子鉴定, gyrB, 毒力基因, 序列分析, Aeromonas hydrophila, molecular characterization, gyrB, virulence gene, sequence analysis

Abstract: Six strains of Aeromonas hydrophila isolated from dying fish were molecularly characterized as well as five virulence genes were detected and analyzed in order to evaluate the feasibility of detecting the virulence genes to infer the potential pathogenicity of A. hydrophila at the molecular lever. 16S rDNA and gyrB gene were used to characterize A.hydrophila, five virulence genes including aerolysin (aer), haemolysin (hly), serine protease (ahp), heat-stable cytotonic enterotoxin (ast) and heat-labile cytotonic enterotoxin (alt) were detected by PCR, and the sequences of gene and virulence were analyzed using Mega 5.2. All of the strains were characterized as A.hydrophila, and four of five virulence genes at least were detected as positive, including the genes of haemolysin and two kinds of cytotonic enterotoxin. By the sequences analysis, we found the amino acid sequences of high similarity among aerolysin, haemolysin and serine protease. A.hydrophila could be well characterized using 16S rDNA and gyrB gene sequences, and the varied virulence genes indicated the potential pathogenicity. Through the sequences analysis, the genes of aer, hly and ahp were relatively conservative, and the encoding virulences were highly conserved. Detecting the virulence genes of aer, hly and ahp could infer the potential pathogenicity of A. hydrophila in the clinical molecular diagnosis.