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

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 sensitivities 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 Aeromonas 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 Aeromonas sobria were close to Aeromonas 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 Ahal, 76.92%. Four genotypes were found in pathogens isolated, being hly+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.