Isolation And Characterization Of Haemophilus Parasuis And Development Of Its Diagnostic Method And Inactivated Bacterin

Haemophilus parasuis is the causative agent of swine polyserositis, polyarthritis and meningitis. As the development of the world pig industry, the disease has become one of the most important bacterial diseases of pigs worldwide. China is a country which raises a large number of pigs, but systemic research on Haemophilus parasuis has not yet been reported. Therefore, it is indispensable and imperative to unravel the epidemiological status in China and develop diagnostic methods and vaccine for Haemophilus parasuis. The study reported here focused on the isolation and characterization of Haemophilus parasuis from China, and development of indirect haemagglutination test and inactivated bacterin, which also provided very important materials for Haemophilus parasuis research and contributed for preventing and control of Haemophilus parasuis of China.The main research included as below:1. Isolation, identification and serological characterization of Haemophilus parasuis isolates from ChinaFrom fifteen provinces and cities in China, 281 strains of Haemophilus parasuis were isolated from swines which characterized by polyserositis and fibrinopurulent polyarthritis, based on morphologic, cultural and biochemical characteristics and Polymerase Chain Reaction (PCR). The typing antisera of 15 international Haemophilus parasuis reference strains was produced and all Haemophilus parasuis strains isolated from China were serotyped both by Kieletein-Rapp-Gabriedson (KRG) Gel Diffusion (GD) test and Indirect Haemagglutination (IHA) test. By combining the GD and IHA results, thirteen Haemophilus parasuis serovars were identified. Serovar 4 (24. 2%) and serovar 5 (19. 2%) were the most prevalent serovars, followed by serovars 13 (12. 5%), 14 (7. 1%) and 12 (6. 8%), while 12. 1% of the isolates could not be assigned to a serovar (nontypable). The results obtained in this study shows that Haemophilus parasuis is widely exist in Chinese pig farms.2. Study on biological characteristics of Haemophilus parasuisSome biological characteristics of Haemophilus parasuis were studied using serovar 4 isolate MD0322 and serovar 5 isolate SH0165 which were isolated and identified in this study. Solid culture medium and liquid culture medium were tested and the culture medium on or in which Haemophilus parasuis grew well was found out. The growth curve of Haemophilus parasuis grew under conditions of 37 °C, 180r/min in Tryptic soy broth and the survival curve of Haemophilus parasuis conserved in three kinds of different solutions at 4°C were detected. Several kinds of bacteria count techniques were evaluated whether it suited to count of Haemophilus parasuis or not. The results obtained in this study are necessary to carry out animal infectious experiments and develop the efficacy test methods of Haemophilus parasuis vaccine.