Protective Effects Of Five Immuno-Regulating DNA Vaccines On Infection Of Eimeria Tenella In Chicken

Avain coccocidiosis causes severe economic loss in the poultry industry. Theemergence of drug-resistant parasites and the drug residues problem restricted thedevelopment of poultry industry so that a new approach to prevent avain coccocidiosisshould be found. It has been approved that stimulating the cell immuno-reaction of the hostis an effective approach to prevent avain coccocidiosis. A prominent advantage of DNAvaccine as a third generation of vaccine is that it can induce abroad cell immuno-reactionand form perdured immune memory. Particularly, the immune regulative DNA vaccinewhich was constructed by special antigen together with some cytokine genes has moreeffect and prospect in the anti- coccocidiosis practice. In this investigation we inserted theMZ5-7 antigenic gene of Eimeria tenella ligated with the chicken cytokine IFN-γ,IL-18into the vector pcDNA4.0 to construct immuno-regulative DNA vaccinepcDNA4.0-MZ5-7-IFN-γ,pcDNA4.0-MZ5-7-IL-18. The protective effects the abovementioned DNA vaccine together with pcDNA4.0-MZ5-7,pcDNA4.0-MZ5-7-IL-2,pcDNA4.0- MZ5-7-IL-17 were tested in the protective experiment of chickens against thechallenge of Eimeria tenellaIPTG was used to induce the expression of pET28b-MZ5-7 constructed in ourlabouratory. Purified MZ5-7 protein was used to immune rats for E. tenelIa MZ5-7anti-serum. The anti-serum was used to check the expression of MZ5-7 DNA vaccine inchicken by western-blot. Designed special primers were used to check the transcription ofMZ5-7 DNA vaccine in chicken by RT-PCR. The results showed that the DNA vaccinescould be well transcripted and expressed in chicken and they could be used to animalprotective experiment.The chicken of protective experiment were divided into eight groups: pcDNA4.0,pcDNA4.0-MZ5-7,pcDNA4.0-MZ5-7-IL-18,pcDNA4.0-MZ5-7-IL-17,pcDNA4.0-MZ5-7-IL-2,pcDNA4.0-MZ5-7-IFN-γ,Unimmunized-unchallenged controlgroup,unimmunized-challenged control group. Each group had 30 chicken and were injected with vaccine through chest muscle. The vaccine was inoculated at 14 days and 21days of age and each chicken was challenged with 5×10~4 Eimeria tenelIa sporulated oocytesat 28 days of age of chicken. All chicken were killed at 35 days of age and the protectiveeffects were estimated by the index of lesion score of caecum, OPG, average body weightgain, anticoccidia index (ACI), The results showed that the immuno-regulative DNAvaccine pcDNA4.0-MZ5-7-IL-18,pcDNA4.0-MZ5-7-IL-2 pcDNA4.0-MZ5-7-IFN-γhadgood protective effects. Separately their ACIs are 188.45,184.47,184.99.