Efficacy of chimeric DNA vaccines encoding Eimeria tenella 5401 and chicken IFN-gamma or IL-2 against coccidiosis in chickens

摘要

Chimeric DNA vaccines encoding Eimeria tenella (E. tenella) surface antigen 5401 were constructed and their efficacies against E. tenella challenge were studied. The open reading frame (ORF) of 5401 was cloned into the prokaryotic expression vector pGEX-4T2 to express the recombinant protein and the expressed recombinant protein was identified by Western blot. The ORF of 5401 and chicken cytokine gene IFN-gamma or IL-2 were cloned into the eukaryotic expression vector pVAX1 consecutively to construct DNA vaccines pVAX-5401-IFN-gamma, pVAX-5401-IL-2 and pVAX-5401. The expression of aim genes in vivo was detected by reverse transcription-polymerase chain reaction and Western blot. Fourteen-day-old chickens were inoculated twice at an interval of 7 days with 100 mu g of plasmids pVAX-5401, pVAX-5401-IFN-gamma and pVAX-5401-IL-2 or 200 fig of recombinant 5401 protein by leg intramuscular injection, respectively. Seven days after the second inoculation, all chickens except the unchallenged control group were challenged orally with 5 x 10(4) sporulated oocysts of E. tenella. Seven days after challenge, all chickens were weighted and slaughtered to determine the effects of immunization. The results showed the recombinant protein was about 90 kDa and reacted with antiserum against soluble sporozoites. The animal experiment showed that all the DNA vaccines pVAX-5401, pVAX-5401-IFN-gamma or pVAX-5401-1-2 and the recombinant 5401 protein could obviously alleviate body weight loss and cecal lesions as compared with non-vaccinated challenged control and empty vector pVAX1control. Furthermore, pVAX-5401-IFN-gamma or pVAX-5401-1-2 induced anti-coccidial index (ACI) of 180.01 or 177.24 which were significantly higher than that of pVAX-5401. The results suggested that 5401 was an effective candidate antigen for vaccine. This finding also suggested that chicken IFN-gamma or IL-2 could effectively improve the efficacies of DNA vaccines against avian coccidiosis. (C) 2015 Elsevier Inc. All rights reserved.