| Summary: | 碩士 === 國立中興大學 === 獸醫病理學研究所 === 88 === To investigate the effect of pseudorabies (PR) virus on pulmonary microenvironment and local immune responses, the experimental pigs (10-week-old) were endobronchially inoculated with PR virus (TW strain, 2 x 106 TCID50) or sterile PBS. At the designed time the bronchoalveolar lavages (BAL), blood samples, and regional lymph nodes were collected for phenotypic and phagocytic assays and pathological study. Pigs inoculated with PRV showed depression, anorexia, and slight respiratory distress on 4 days postinfection (dpi) and those symptoms were persistent until 11 dpi. Histopathological lesions on PRV infected pigs displayed mild nonsuppurative meningoencephaltis, broncho-interstitial pneumonia with mild focal necrosis at 4, 8, and 11 dpi. The trachobronchial lymph node showed focal necrosis and lymphoblast hyperplasia in T cell dependent areas on 8 and 11 dpi, and then hyperplasia of lymph follicles on 32 dpi. The neutralizing antibody in blood and concentrated BAL fluid were present on 7 and 11 dpi, respectively. Studies on phenotype of PAM showed an increase in the expression of MHC class I and MHC class II in both control and PRV infected pigs 4 dpi. The phagocytic function of PAM to P. multocida on both control and PRV-infected pigs was suppressed after endobronchial inoculation, but the effect was more serious and recovered slowly on PRV infected pigs than controls.
When we looked at the changes and the activation of lymphocytic subpopulations of blood and middle tracheobronchial lymph node, a dual staining of lymphocytes was performed. The relative percentages of CD4 and CD8 subpopulation during acute PR virus infection were not significantly changed. However, the subpopulation of CD4+CD8+ were markedly increased at recovery stage of PRV infection. Moreover, the results also exhibited more CD4+ and CD8+ lymphocytes expressing MHC class II molecules after PRV infection in blood and regional lymph node. In contrast, the expression of IL-2R was not significantly increased in CD4+ and CD8+ lymphocytes during acute infection. Those data conclude that the suppressive effect of phagocytic function of PAM during acute PR virus infection may contribute to the secondary infection in pulmonary disease. The increase in CD4+CD8+ and more MHC class II expression on lymphocytes after PRV infection may reflect the activated state of lymphocytes during acute phase and then return to memory state at recovery stage. However, the less expression of activation marker, IL-2R, on lymphocytes during acute phase that was not matched to the pathological changes of node is remained further elucidated.
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