| Haemophilus parasuis is an infectious disease caused by a contact bacterial named Haemophilus parasuis (Haemophilus parasuis, HPS) of porcine, which threating to the healthy development of pig industry. For a long time, because of the complex situation of HPS serotypes, the difficult preparation and non-standard method of serum type, This experiment adopted the HPS standard strains of 15 serotypes to immunize the healthy male rabbits for the preparation of HPS serotype, and the agar diffusion test for serotype identification of HPS field isolated from Sichuan province for the benefit of the disease etiology diagnosis, These experiments were aimed to investigate the prevalence of the HPS dominant serum and the serotype distribution rule in Sichuan province area, which could provide a scientific reference for this disease as a targeted prevention.1. Screening and optimization of HPS typing sera prepared by immune procedureThe standard strains of 15 serotypes of HPS were purchased from the Australian Queensland animal research center. Then, these standard strains were been recovered and identified, These results could lay a foundation for the preparation of Typing sera. Based on the optimized original laboratory immunization program, the improvement of bacteria immune times, the shortened immune intervals and the decreased immune dose were induced by the program, while basic immunization increased before immune induction. Based on the optimizational original experimental immunization program, the HPS5 type standard strains were used to prepare immunogen. At the same time,3 different immune procedures based on literatures were used as control group. After immunity, the blood was collected from heart, the serum was separated, diffusion test were used for specific detection, the IHA kit was used for the detection of antibody titer. Results showed that: good serum specificity, significant precipitation lines in serum of rabbits appeared between experimental groups and control groups from agar gel diffusion test, while there were no precipitation lines in control groups. And the serum antibody titer in experimental groups reached 1:32, higher than the other 3 groups, therefore, the optimized immune program can be extended for HPS other serotype typing serum preparation.2. Preparation of antisera to different serotype of Haemophilus parasuis and its clinical applicationImmunogen was prepared from the 15 serovars of Haemophilus parasuis standard strain, which was used to immune male rabbits by subcutaneous and ear vein injection. After the immune procedure, the blood serum was separated by the hemospasia from the heart, and detected for serum specific and antibody titers. Results showed that the serum specific was good, and the serum antibody titers was greater than 1:8, which indicated the separated serum could be used for serovar identification.498 pathological materials were collected from 80 pig farms of 22 cities of Sichuan province by our laboratory, from which 80 HPS was identified. The serovar of 80 HPS was identified by agar diffusion test, which showed that serovar 4 accounted for 28.75% (23/80), serovar 5 accounted for 35.00%(28/80), serovar 12 accounted for 6.25% (5/80), serovar 13 accounted for 7.50%(6/80), serovar 15 accounted for 1.25% (1/80)and non-typable strains accounted for 21.25% (17/80)from the 80 filed isolates. These results indicated that serovar 4,5,12 and 13 were the predominant serovar in the source areas of the isolates, which could be provided a reliable theoretical basis for the detection of the prevalence of HPS from Sichuan Province and screening of the vaccine strains. |
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