| The Bovine Viral Diarrhea/Mucosal Disease is caused by Bovine Viral Diarrhea virus/Mucosal Disease virus (BVDV/MDV), which characterized by fever, ulcers, and desquamation in mucosal of digestive tract, hemorrhagic inflammation, diarrhea, transient leukopenia and reproductive failure. The persistent vermeil animals are specifically immunosuppression and enhance the pathogenicity of other agents. The disease lead to persistently infect with BVDV easily, which causes immunological suppression and Secondary infection by other pathogens. Bring greatness infection to cattle breed. This paper investigate and study the epidemiologist of Bovine Viral Diarrhea/Mucosal Disease and the identify of pathogen to Sichuan province, according as there are affinity characteristic between the BVDV/MDV and HCV, introduce the produce course of HCV bacterin, we are immunity the cattle by HCV bacterin, study the production ability and security and immuno-responsion of cattle to the HCV bacterin. It will be helpful for offer the theory base that HCV bacterin can prevent and control the BVD/MD.The mail results are showed as follows:1 To have a definite objective in view, we collected serum samples from cattle herds and yak herds in the partial regions of Sichuan province for examining the antibodies against BVD/MD with a cell neutralization test. Although there was the prevalence of cattle and yak with BVD/MD in Sichuan province at early 1980' s, we found that there was still prevalence of cattle with BVD/MD in Chengdu and yaks in Ganzi and Aba prefectures. Serologic investigation showed that BVD/MD positive detectable rate of cattle herds reached 34.8%, of which the infection rate was 40% for the adult cattle and 25% for calves. The average of BVD/MD positive detectable rate of yak herds reached 37.5%, of which the infection in some areas reached above 60%. The pathogen of yak (the strain I of yak), which isolated through using immnunoelectronic microscope and immunofluorescence techniques, is consistend with the standard strain of Oregon C24V on characteristics of physical chemistry and biology. The difference between two viral strains is that the strain I of the yak belongs to NCP BVDV/MDV, however, the calves vaccinated with this strain can duplicate classic case of BVD/MD. It proved that there are two biology model CP and NCP of BVDV, and they can transform one another.2 In order to know and master the capability and the titer of the attenuated HCV vaccine, we investigated the process of the manufacture and the checkout of HCV vaccine on the spot in the manufactory. After comparison and investigation, the attenuated lyophilize vaccine of HCV (attenuated vaccine of HCV I ) was finally selected as the vaccine used in yaks because this vaccine have some advantages in higher immunity which is higher than the immunity of cell-mediated vaccines of HCV, the lower price which is lower than the lymph-spleen-made vaccines of HCV (0.2 yuan per dosage). This provides a possibility for extension in commercial system. Also the vaccine has not toxic effect and does not affect the production performance.3 Various times dosages (3-25 times dosage) of the attenuatedlyophilize HCV vaccine were injected to lactating cows, pregnant cows, calves and yaks (including male and female). The body temperature, food intake, milk yield and activities of these animals were recorded for a period of 15 day pre- and post-treatment. Meanwhile, the amount and sorts of the blood corpuscle were checked. The detailed results of the study is as the following: (1) After injection of 18 times dosages of the vaccine to 1-11 month-old calves, these calves have normal activity, body temperature and food intake. None of theses animals was died and occurred toxic effect. (2) After injection of 10 times dosage of the vaccine to 8 pregnant cows at gestation period of 1-7 month, these cows have normal activity, body temperature and food intake. None of theses animals aborted and all of them parturited as normal. (3) After injection of 25 times dosages of the vaccine to adult yaks (...
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