Identification of Pathogen of Skin Rot of Rana spinosa and Study on Immune Effect of Vaccine

Abstract

In order to determine the pathogen of the skin rot disease of Rana spinosa and provide theoretical basis for the prevention and control of the disease in production, this study isolated the pathogenic bacteria from the diseased frog focus, carried out artificial infection and the morphological characteristics, physical and chemical characteristics and molecular biological analysis of the pathogenic bacteria, and carried out drug sensitivity test and vaccine immunity and control test. The results showed that the dominant bacteria QS01 isolated from the diseased lesions of Rana spino-sa was confirmed to be the pathogen of skin rot disease of Rana spinosa by artificial regression infection test. Combined with its phenotypic characteristics and 16S rRNA, gyrB gene sequence analysis, it was determined to be Citrobacter freundii . The medicine sensitive test result showed that the bacteria is sensitive to eight kinds of antibiotics including Enrofloxacin, Chloramphenicol, Ceftazi-dimeetc, but lowly sensitive or resistant to other tested antimicrobial agents. Adopting these ways included injection, immersion and atomizing to inoculate frog with vaccine named QS01 inactivated by formaldehyde, average titer of three immunity groups reached the peak in the 20 d. The highest serum antibody titers were 1:64~128 (101.6), 1:16~32 (20.2) and 1:16~32 (16), which were significantly higher than those of the control group. The immune protection rate for Q. spi-nosa after injection, immersion and spray of QS01 inactivated vaccine can reach 100%, 85.71% and 71.43%. Our research shows that Citrobacter frederii is the pathogen of skin rot disease of Rana spinosa , and it is effective and feasible to use vaccine to control ulcerative skin disease.