Cloning And Expression Of ApxⅢA Gene Of Actinobacillus Pleuropneumoniae And Determine Immunogenic Activity Of Toxion Factor

Porcine contagious pleuropneumonia(PCP) is a highly contagious disease that is caused by Actinobacillus pleuropneumoniae(APP) and characterized by severe fibrinous necrotizing hemorrhagic pleuropneumonia in pigs. Since this disease was discovered in 1957, it spread in the worldwide and caused important economic losses in industrialized pig production. Because APP has resistance, vaccination has been a main measure to prevent PCP. At present, an inactivated whole cell vaccine is mostly applied for PCP prevention and treatment in China. But APP has 15 serotypes, so the protection efficacy of inactivated vaccines is unfavorable and developing novel vaccine has become a research hotspot. Developing new generation vaccines become an ideal research direction.Applying recombinant technique, three toxic factors of APP were expressed, then constructed one multi-components recombinant subunit vaccines and assessed their protective efficacy in this study. It had been proved that ApxI, ApxIII and Omp was more important toxic factors and immunogen, which had been studied as vaccine component.1 Constructing the ApxIIIA expression vector, ApxIA and Omp gene was subcloned into the expression vector PET-ApxIA and pPRo -Omp, yielding the recombinant plasmid PET-ApxIIIA, PET-ApxIA and pPRo -Omp, which were transformed into E.coliJM109 (DE3) and induction with IPTG. three expected proteins were properly expressed. The proteins was immunogenic by Western blot analysis.2 The rabbit were immunized with recombinants of rApxI, rApxIII and r Omp (group I); that of rApxI, rApxIII, rOmp and viable organism (groupII); inactivated vaccine of Actinobacillus pleuropneumonia (APP) serotype 1,3 and 7 (groupIII); PBS (control group), After detecting antibody titers, the immune protection efficacy of multicomponent recombinant subunit vaccines was assessed. Results showed that the levels of antibodies, group II were significantly higher than those of the other two groups, but levels of antibodies of group I lower than groupIII . sera titers reached highest dilution to 1:256.