Effects Of The PRRS Attenuated Strain Immunization By Nasal Route On The Pig's Local Respiratory Tract And System Immune Responses

In order to investigate local respiratory tract and system immune reaction, PRRS attenuated strain were used to immune pigs by nasal and muscle injection route. The pigs were cross-fertilize of Yorkshire and Landrace. To investigate the local cellular immunity in the respiratory tract, the numbers of intraepithelial lymphocyte (IEL) and the level of IL-2 in tracheas were detected; To investigate the local humoral immunity, the level of SIgA in the nasal cavity secretion and the numbers of IgA and IgG secreting cells in tracheas were detected; To investigate the level of the systemic immune reaction, the level of IgA and the specific antibody in the serum were detected. The result as follows:1 The effects of PRRS attenuated strain immunization by nasal route on the local cellular immunity in respiratory tractThe numbers of IEL in tracheas and bronchia: Histologic technique was applied to detect distribution and numbers of IEL. IEL of bronchia and tracheas distributed in bronchia mucosal epithelium and in tracheas mucosal epithelium, especially in bifurcation of tracheas. The results showed that the numbers of IEL in tracheas was increased significantly (P<0.01) with PRRS attenuated strain immunization by nasal route contrast to muscle injection and control group; There are no significant changes between muscle injection group and control group (P>0.05) . The numbers of IEL in bronchia had no significant changes ( P > 0.05 ) in three groups. The results suggested that by nasal route immunization with the PRRS attenuated strain may arouse significant trachea local cellular immunity, but muscle injection could not.The level of IL-2 in tracheas: Radioimmunoassay was applied to detect the level of IL-2 in tracheas. The results showed that the level of IL-2 in tracheas of nasal cavity immunization group increased significantly (P<0.01) compared to muscle injectionimmunization group and control group after immunization with PRRS attenuated strain; but muscle injection group compared to control group had no significant changes (P>0.05) . The results suggested that by nasal route immunization can improve the level of cytokine IL-2 in tracheas, but muscle injection could not have effects on mucosal cytokine.2 The effects of PRRS attenuated strain immunization by nasal route on the local humoral immunity in respiratory tractThe level of SIgA in the nasal cavity secretion: Double sandwich enzyme-linked immunosorbentassay was applied to detect the level of SIgA in the nasal cavity secretion. The results showed that the level of SIgA in the nasal cavity secretion increased significantly (P<0.01) compared to the control group at the third, the forth and the fifth week after immunization by nasal route with PRRS attenuated strain, but there have no significant changes in muscle injection group and the control group. The level of SIgA reach peak at the third week after immunization by nasal route with PRRS attenuated strain and lasting test over. The results further suggested that it can improve humoral immunity of local tracheas by nasal immunizationThe numbers of IgA and IgG secreting cells in tracheas and bronchia: Immunohistochemical technique was applied to investigate the distributing of IgA and IgG secreting cells in tracheas and bronchia. The results showed that IgA and IgG secreting cells mainly distributed in the lamina propria, the surfaces of tracheas and bronchia have positive reaction. The numbers of IgA and IgG secreting cells in tracheas increased significantly compared to muscle injection group and control group (P<0.01) . In bronchia there are no apparent changes among nasal cavity immunization group, muscle injection group and control group. The results suggested that mucosal immunization by nasal route could improve the humoral immuniy reaction in the local of tracheas.3 The effect of PRRS attenuated strain immunization by nasal route on the immune levels of systemThe level of IgA in serum: Double sandwich enzyme-linked immunosorbent assay was applied to detect the level of IgA in the serum. The level of IgA in the...