| Summary: | 碩士 === 國立嘉義大學 === 獸醫學系研究所 === 100 === Porcine circovirus associated disease (PCVAD) is a common disease in Taiwan pig farms. The aim of this study was to evaluate the protective efficacy of PCV2 vaccine by determining the pathogenic loads in various tissues and sera after vaccination(AV) in the field pigs. Three hundreds 4-week-old pigs were divided into vaccinated and control groups, with 150 pigs each in three pens respectively in the same house. In each group, 20 pigs were also randomly selected and ear-tagged. Among them, four pigs in each group were humanely euthanized at days 0, 7, 21, 35 and 49 AV. Growth performance, gross lesions of the lung and turbinate, specific and non-specific antibodies of sera and pathogenic loads of various tissues and sera were grossly observed and examined by ELISA and real-time PCR (qRT-PCR). The results showed that the pigs in vaccinated group got 3.9 Kg more body weight and 2.3 % lower mortality than those in control group at the end of the experiment. At days 49 AV, significant differences were noted between these two groups in gross lung lesions, non-specific IgG ELISA titers and specific PRRSV antibodies as well as PCV2 viral loads in the lung, spleen, and lymph node, PRRS viral loads in the lung, spleen, lymph node and sera and Mhp loads in spleen and sera. Also, non-specific IgA at days 21 and specific PCV2 antibodies at days 35 and 49 AV, and Pm loads in the lung, spleen, and lymph nodes at days 7, 21 and 35 AV were significant different between these two group. Although no significant difference (P>0.05) observed in gross lesion of turbinate, microscopically interstitial pneumonia and peribronchiolar lymphoid hyperplasia of the lung, and lymphoid depletion of lymph nodes, the pigs in vaccinated group had shown a better performance than those in control group in many evaluation system as described above. Taken together, the usage of PCV2 vaccine in field pigs might prevent other pathogenic infection by enhancing pigs’ immunity and finally reducing the amounts of other pathogens in tissues and sera, and the severity of the lung lesions.
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