Abstract:

The study was conducted to analyse an epithelial cell oxidative damage of a pathogenic Mycoplasma hyopneumoniae strain 168 and attenuated strains 168L in vitro.M.hyopneumoniae strain 168 and its attenuated strain 168L were used to infect the swine alveolar epithelial cells (SJPL) in vitro.To determine an appropriate time of infection and infection dosage，both nitrogen monoxide (NO) from the supernatant of the infected cell and 3-(4,5Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were measured.To verify the injury model，an indirect immunofluorescence (IFA) was used to detect the Mhp on the cell，cell damage were evaluated by detecting the hydrogen peroxide (H₂O₂) and 4′,6-diamidino-2-phenylindole (DAPI).Results were as follows：The optimizing infection time is 36 h post-infection and the infectious dosage is 5×10⁶CCU.The NO in the supernatants of the infected cells was significantly higher in the infected cells by Mhp168 compared to Mhp168L strains (P<0.05) in the same cell viability.The H₂O₂  detection shows that Mhp168 and Mhp168L oxidative damage to cells was significantly higher than the control (P <0.01).It also demonstrated a significant differences (P <0.05) in oxidative damage between Mhp168 and Mhp168L infected cells.The results of IFA and DAPI showed that the Mhp168 adhered to cells exceed that of Mhp168L and the extent of damage to cells is also larger.The analysis of oxidative damage of SJPL cells infected by Mhp in vitro offers a basis for the further study of the infection mechanism of different Mhp strains to cell.