Study On Preventive Measures For Aeromonas Hydrophila And Aeromonas Sobria In Rice Field Eel (Monopterus Albus)

Rice field eel (Monopterus albus) is rich not only in nutritional value but also in medicinal value, so it is popular among consumers. Currently it is bred around the country except Tibet and the Three Northeastern Provinces, especially in Sichuan, Hubei, Jiangxi. Because China has just made a start in Rice field eel farms, on the other hand, more attention has been paid for breeding and feeding, people failed to prevent disease in Rice field eel farming industry. Rice field eel Aeromonas hydrophila and Aeromonas sobria are two major pathogenic agents of Rice field eel, and the mixed infection of them is common in Rice field eel, so bivalent vaccines and Chinese herbal medicine which can prevent Rice field eel from both two pathogenic agents are urgent need for Rice field eel culture development. In this study, a bivalent vaccine against Aeromonas hydrophila and Aeromonas sobria was produced, and its immune efficacy was evaluated. In addition, the antibacterial activity of Chinese herbs against Aeromonas hydrophila and Aeromonas sobria was tested. 1 Optimization of inactivation of Aeromonas hydrophila and Aeromonas sobriaChose different nutrient sources, different incubation temperature, different pH values to determine the optimal culture conditions of Aeromonas hydrophila and Aeromonas sobria.The results showed that optimal culture conditions of Aeromonas hydrophila were:Ordinary broth with 1% tryptone, the temperature was 37℃, pH= 7.5; the optimal culture conditions of Aeromonas hydrophila were:Ordinary broth with 1% tryptone, the temperature was 28℃, pH was 7.5. Mixed the two kinds of bacteria according to 1:1 propotrtion after expanding them, then joined 0.2% formalin (finally density), deactivated at 28℃for 36h to produce the two joint deactivation seedlings of which precipitation line was the strongest.2 Immune responde of Rice field eel to Aeromonas hydrophila and Aeromonas sobria bivalent vaccineThe bivalent vaccine composed of Aeromonas hydrophila and Aeromonas sobria. The immunogenicity of bivalent vaccine was tested by examining the antibody titer,IgM, lysozyme activity, contents of alexine C3 and the challenge test of live pathogen was carried out, too. Results showed that:antibody titer in eel immunized with bivalent vaccine was induced, after 4 weeks came to a head, then declined. After strengthening immunization, the antibody titer reached the peak value (26.67 Against Aeromonas hydrophila and 26.67 Against Aeromonas sobria) after the first 6 weeks post-immunization, and then began to decline. IgM, lysozyme activity, contents of alexine C3 after immunization reached 0.5020±0.008mg/mL,12.27±0.17ug/mL, 33.96±0.15U/mL,0.1054±0.0049 mg/mL separately.The challenge test of both pathogen was also carried out 8 weeks after immunization, the relative survival to Aeromonas hydrophila and Aeromonas sobria challenge were 56.67% and 46.67% separately. Results indicated the bivalent vaccine can effectively protect eel from Aeromonas hydrophila and Aeromonas sobria infection.3 Immunization efficacy of Compound Adjuvant for Rice field eelAdding compound adjuvant enhanced the immunogenicity of vaccines. After the first immntity, the specific antibodies of the anti- Aeromonas hydrophila and Aeromonas sobria were tested in a week.At the same time, the antibody titers and the immune protective rate of the compound adjuvant+bivalent vaccine Group were the highest. The results indicated that APS and LMS could protect eel from the infection of Aeromonas hydrophila and Aeromonas sobria.4 antibacterial activity of Chinese herbal against Aeromonas hydrophila and Aeromonas sobriaAdopting the Oxford cup method and dilution method, Selected Rhus chinesis, Scutellaria baicalensis, Populus canadensis Mocnch, Forsythia suspense, Pheum officinale and other kinds of Chinese herbal, in vitro, to inhibite the growth of the 10 strains of Aeromonas hydrophila and 1 strain of Aeromonas sobria which were isolated from the sick eel. On this basis, selected five Chinese herbal to compound four prescriptions (A, B, C, D) according to the characteristics of Veterinary compatibility and selected one strain of Aeromonas hydrophila and one strain of Aeromonas sobria to make the vitro antibacterial test. The results showed that the two pathogens were sensitive to the Rhus chinesis, Scutellaria baicalensis, Populus canadensis Mocnch, Forsythia suspense, Pheum officinale and the inhibitory effect of Rhus chinesis was the most significant. The inhibition zone diameter was more than 20mm; The four complex prescriptions had the effect on antimicrobial.The effect of A complex prescription on inhibitting the growth of Aeromonas hydrophila and Aeromonas sobria was better than the others.