Edwardsiella Tarda Infection On Andrias Davidianus And The Protection Of Dead Vaccine At Primary Immune

Objective:To investigate the pathogenicity of Edwardsiella tarda on andrias davi dianus and the protection of dead vaccine at primary immune.Methods:The dead vaccine of Edwardsiella tarda prepared by formaldehyde was harmless by toxicity test on mouse.15 andrias davidianus weight from 25 grams to 300 grams were randomized into 5 groups, Which are:control group, infection group, immune group(107 per ml,108 per ml,109 per ml).At the first week control group and infection group were given 0.1ml saline through intramuscular, immune group were given 0.1ml formaldehyde inactivated vaccine,which were 107 per ml,108 per ml,109 per ml respectively. At the 7th week every group excep control group were given 0.1ml 107cfu/ml viable edwardsiella tarda.48 hours after attacked, the bacterium distribution was detected by indirect immunofluorescence and the apoptosis rate of liver and spleen was detected by TUNEL.Results:Andrias davidianus infected by Edwardsiella tarda reduced activities and left the gatheting place to stay alone.Fluorescent material could be seen in liver, spleen on infection group and immune group. The apoptosis rate of infection group in the spleen and liver was higher than control group and the difference was significant (P<0.05).The difference between immunization groups and control group,The difference between immunization groups and infection group,the difference in immunization groups had no significant groups (P>0.05).Conclusion:(1)Intramuscular injection untypical viable edwardsiella tarda cells 0.1ml 107cfu/ml could cause andrias davidianus rinfection; the bacterium can be detected in liver and spleen; (2) Apoptosis may be one of the reason that edwardsiella tarda infect andrias davidianus. (3)The protection of dead vaccin at primary immune is not good.