Preparation And Application Of Agglutination Antigen Of Pullorum Diseas

Pullorum is an infectious disease that caused by Salmonella to chickens of various day-age. The characteristic is acute and septic course of disease or chronic and invisible infection. There is no effective or reliable vaccine against the disease at present. Diagnostic antigen is commonly used for purification of pullorum disease at home and abroad. China’s standard antigen is manufactured using standard serum to control the bacterial concentration of antigen, which leads to unstable results of antigen detection in different batches. Based on the issues, this article studied the colony types and serotypes of51strains of Salmonella pullorum isolated from chickens to find out the internal relations between the colony types and serotypes, and then filtered out the strains for antigen preparation. The optimal bacterial concentration of antigen was determined, and its detection effect was compared with the standard antigen. Finally, newly manufactured antigen was applied in the clinical detection.The main conclusions were as follows:1Screening of Salmonella pullorum strains preparation for agglutination antigenThe research studied the colony types and serotypes of51strains of Salmonella pullorum isolated initially from chickens to find out the internal relations between the colony types and serotypes, and screened of the strains preparation for agglutination antigen, then tested the mutation rates of colony types and serotypes of the strains in culture medium after continuous passage. The results showed that, three kinds of colony types YBc, yBC and Ybc were the major colony types isolated for the first time, YBc and Ybc colony types of strains contained the most abundant O:123antigen factor, while yBC colony type of strain had the most abundant O:122antigen factor. According to the results, three types of strains for antigen preparation were selected. The results of mutation rates of the selected and unselected strains with the same colony type showed that, the selected ones were more stable and their mutation rates were reduced after screening.2Standardization of pullorum agglutination antigenUsing the staining antigen with different concentrations of bacteria to detect the artificially and naturally infected chickens respectively, and acted with different dilutions of pullorum hyperimmune serum by standard tube agglutination test and flat agglutination test, in order to compare the detection effect of staining antigen with different concentrations of bacteria in the artificially and naturally infected chickens, as well as in the different dilutions of pullorum hyperimmune serum. The results showed that the positive rate of staining antigen with bacterial concentration of20billion per mL was the highest, reaching96.2%, the response was faster and clear, and the result was in accordance with the standard tube agglutination test. The naturally infected chickens showed positive results also had pathological changes and positive bacterial isolation. The test range of staining antigen for positive serum was quite wide. As a result, we used the pullorum agglutination antigen with bacteria concentration of20billion per mL.3Experimental test and clinical application of the pullorum antigen agglutinationThe artificially infected chickens of different day-age were detected by self-developed antigen and standard antigen at the same time to compare their positive rates. Meanwhile the naturally infected chickens of different species were also detected by self-developed antigen and the result was compared with that of agar diffusion test to determine the antigen’s specificity and sensitivity. Based on the self-developed antigen, a serological survey of pullorum was carried out in a breeding chicken farm. The results showed that, the detection effect of self-developed antigen in three batches of artificially infected chickens of different day-age was a little better than that of current standard antigen. The results of whole blood plate agglutination test of five species chickens showed that the sensitivity of staining antigen was99.2%, and the specificity was100%. Compared with agar diffusion test, it was found that the quarantine effect of agglutination was credible. In clinical application,2059breeding chickens were detected by self-developed agglutination antigen, and the average positive rate was11.9%. The results showed that different gender and different species of chickens had different infection rates, which were significantly higher in roosters than those in hens.