Development Of An Animal Model Of Haemophilus Parasuis And Localization Of Haemophilus Parasuis In Model Animal

Haemophilus parasuis is the pathogen of Classer′s Disease in pig, which could cause the polyserositis, arthritis and meningitis. In recent years, this disease has become increasingly significant in the world with the development of the pig production, and brought large economical loss to the industry. The etiologic and epidemiological analysis showed that the disease occurred in 1995 and has spread all over in China. And it has become one of the important diseases caused by bacteria and made a strong impact on the pig production. The serotypes 5 reference strain of Haemophilus parasuis(Strain Nagasaki) was inoculated into the liquid culture medium in this experiment. Haemophilus parasuis was cultured under the condition of 37℃, 200r/min. Then the liquid culture medium was selected at various time and concentration and the animals were inoculated, and the optimal time of Haemophilus parasuis was explored in the liquid culture medium to infect. Furthermore, the experiment of the pathogenicity was conducted on using different laboratory animals including SPF mice, SPF rat, SPF golden hamster, SPF guinea pig and clean guinea pig and clean rabbits through Strain Nagasaki infection, for selecting susceptive. The experimental infection of the impressionable animals was conducted and the changes of clinical and pathological characteristics were observed. Then the changes of clinical and pathological characteristics on the impressionable animals were compared with target animalˊs lesions, and the isolation and identification of the pathogen in vivo. Therefore, an animal model of Haemophilus parasuis was primarily found. The animal model was infected by 1.30×109CFU (0.2ml) through its trachea. At 6h, 8h, 10h, 12h, 13h, 14h and 16h after infection respectively, the animals were dissected. The important organs, including the brain, heart, liver, spleen, lung and kidney, were selected to inspect the distribution and migration of Haemophilus parasuis in vivo of the animal model, by combination the immunohistochemistry methods with recovery Haemophilus parasuis . The results showed the optimal time stage was when the bacterial number was up to 109CFU/ml or more after inoculating 10h to 13h. The guinea pig was the most susceptive animals to Haemophilus parasuis among the several animals. After comparison on the changes of clinical and pathological characteristics in the guinea pig and the pig, the similar characteristics both occurred in the guinea pig and pig. Therefore, the guinea pig was primarily regarded as more prefect animal model of Haemophilus parasuis. The results of inspection by the immunohistochemistry methods were followed. Haemophilus parasuis was light positive in the lung 6h after infection, and positive in the lung and kidney 8h after infection, and positive in the liver and spleen 10h after infection, and positive in the heart 12h after infection, and positive in the brain 14h after infection. Therefore, the experiment provide the theoretical basis for studying the mechanism of occurance and diagnosis and immunity of Classer′s Disease.