Potentiation of Immunity of Piglets to Mycoplasma Hyopneumoniae Vaccine with Fused Gene for Pig IL-4 and IL-6 Embodied in Chitosan Nanoparticles

The novel reco mbinant euka ryotic VRPIL4/ 6 p lasmid, the secretory VR1020 vector containing fused pig IL-6 and IL-4 genes, was encapsulated with chitosan nanoparticles (CNP) prepared by use of ionotropic gelat ion method and then used to inoculate intramuscularly forty 14-day-old piglets using 0.5, 1.0 or 1.5 mg/per anima l, which were simu ltaneously injected with inactivated Mycoplasma hyopneumoniae vaccine and challenged on 10 weeks post vaccination, which were designated as group A1, A2 and A3. Blood was collected every two weeks fro m the piglets after vaccination to detect the changes in immunoglobulin, specific antibod y, IL-2, IL-4, IL-6, IFN-γ and immune ce lls. Co mpared to the control piglets with VR1020-CNP, the concentration of Ig G, IgA and IgM, specific antibody, interleukins and IFN-γ significantly increased in the sera of the groups treated with the fusion genes fro m 14 to 70 days after vaccination (P<0.05); furthermore, the nu mber of T_H, T_C and CD3⁺ T ce lls was raised significantly in the blood of the treated piglets (P<0.05). Meanwhile, the ly mphocytes and monocytes also significantly rose in the treated groups (P<0.05). The hu mora l and ce llu lar immune inde xes of the A3 group increased to different e xtents in co mparison with those of A 1 and A 2 group fro m 14 to 56 days post inoculation (P>0.05 or P<0.05). The protection against challenge with viru lent M hyo and growth performance of the treated pigs is markedly better than those of the control anima l (P<0.05). These results indicated that VRPIL4/6 entrapped with CNP can enhance the humora l and cellu lar immunity of pigs to Mycoplasma hyopneumoniae vaccine, and elevate the immunoprotection level of treated anima l, wh ich could facilitate the development of effective immunoadjuvant against Mycoplasma hyopneumoniae of pig.