The Pathogen Research Of Crucian Carp Big Red Gill Disease And Carp Hematopoietic Organ Necrosis In Sheyanng

Allogynogenetic crucian carp big red gill disease and carp hematopoietic organ necrosis are the most two common and detrimental diseases in allogynogenetic crucian carp breeding in Sheyang District,Jiangsu Province.However the study of allogynogenetic crucian carp big red gill disease has been always stayed at the initial stage, and the outbreak of the disease on a large scale also failed to gain enough attention. The current study has not been able to determine the true pathogen, and the prevention and treatment of the disease also remains at the fumbling stage. Therefore,it waits for breakthrough to determine the pathogen and make effective prevention and treatment system. This research collects typical sick allogynogenetic crucian carps that have big red gill disease in the disease occurring place and then conducts disease pathogen isolation, identification and pathogenicity analysis, to provide scientific reference for the research, prevention and treatment of the disease. Carp hematopoietic organ necrosis is the most popular and most detrimental major disease in allogynogenetic crucian carp breeding in recent years. The present research confirmed its pathogen to be Cyprinid herpesvirus2, CyHV-2. Nevertheless, there has been no current report for the secondary infection caused by carp hematopoietic organ necrosis.This research collects sick carps that have hematopoietic organ necrosis in the disease occurring place and conducts disease pathogen isolation, identification and pathogenicity analysis, to explore the possibility of mixed infection of carp hematopoietic organ necrosis. Enrofloxacin hydrochloride is the most commonly used fluoroquinolone antibacterial drugs in treating cultured allogynogenetic crucian carp bacterial diseases in Sheyang District, but the long-term use of it can lead to the strong drug resistance of the cultured allogynogenetic crucian carps. This research adopts high performance liquid chromatography and tests the pharmacokinetics and the enrofloxacin hydrochloride residual amount in allogynogenetic crucian carps when feeding them to the mouth 20 mg/kg enrofloxacin hydrochloride one single time in 15 ℃ temperaturecondition. It aims to provide reference for the reasonable use of enrofloxacin hydrochloride and the safety of aquatic products. The main results of the research are as follows:Collect sick allogynogenetic crucian carps that have big red gill disease. Gain two strains of dominant bacteria that has been purified by the regular method of isolation. Through the artificial infection experiment results and with reference to the“the Jay’s handbook of bacteria identification”, together with the 16 sRNA part gene sequencing identification, it is confirmed that the two strains of dominant bacteria extracted in this research are both aeromonas hydrophila(A.hydrophila). Integrating the result and data of this research, we confirmed through analysis that A.hydrophila is the pathogen of allogynogenetic crucian carp big red gill disease.In the August of 2015, many farms in Jiangsu Sheyang has occurred the massive death of cultured allogynogenetic crucian carps. The main symptoms of the disease are: severe bleeding of the gills of the sick carps, exophthalmos, a large number of ascites after anatomy, no food in the intestinal canal, pale and swollen liver, and the internal organs has different degree of blood congestion. Isolate the pathogenic bacteria and pathogenic virus of the sick fishes by the regular method;Identify the pathogenic bacteria and pathogenic virus through the artificial infection experiment and the molecular biological method. At the same time, set a bacteria-virus mixed infection experiment to detect the expression law of virus in mixed infection. The result of the artificial infection experiment shows that the YC140621-1 bacterial strain extracted in this experiment has strong pathogenicity to healthy allogynogenetic crucian carps. Combining the analysis of the phenotypic biological characteristics of the isolated bacteria and the 16 s rRNA result, this bacteria is identified to be A.hydrophila.The PCR result identifies the virus extracted in this experiment to be Cyprinid herpesvirus2, CyHV-2. The mixed infection experiment indicates that YC140621-1and Cyprinid herpesvirus2, CyHV-2 in the mixed infection experiment are apparently higher than Cyprinid herpesvirus2, CyHV-2 in single infection. Combined with the result of this research, we conclude through analysis that carp hematopoietic organ necrosis has the possibility of mixed infection.The drug-time curve of enrofloxacin hydrochloride in the blood and different issues both conforms to the 2 rooms open model. Enrofloxacin hydrochloride can be absorbed very quickly in the allogynogenetic crucian carp body and distributed all overin the blood and various issues. The equation of its pharmacodynamics is C=5.056e-0.012t+19.041e-0.011 t, and the absorption half life period(T1/2α) of enrofloxacin hydrochloride in the blood, muscles, liver and kidney is 0.176, 0.562, 4.562 and1.477 h,respectively. The elimination half life(T1/2β) is 69.492, 65.303,218.412 and163.937 h, respectively. The overall elimination rate(CL) is 0.495, 11.181, 10.789 and 7.102 L/h/kg, respectively. The area under the drug-time curve(AUC) is 81.550,1277.55,807.470 and 1432.150 ug/L/h,respectively. According to the regulation that the maximum residue limit of enrofloxacin hydrochloride in edible tissues is 100 ug/kg for the standard, it is advised the withdrawal period be more than 26 days.