论文部分内容阅读
Avian coccidiosis is mostly caused by mixed infection of several Eimeria species under natural conditions and immunity to avian coccidiosis is largely dependent on T-cell immune response.In this study,14 T-cell epitope fragments from 8 antigens of Eimeria tenella(E.tenella),Eimeria necatrix(E.necatrix),Eimeria maxima(E.maxima)and Eimeria acervulina(E.acervulina)were ligated with pVAX1 producing 14 monovalent DNA vaccines respectively.Protective immunity of the monovalent DNA vaccines was assessed by in vivo challenge experiments and then 4 most protective fragments of each species were chosen to construct multivalent epitope DNA vaccines with or without chicken IL-2 as genetic adjuvant.Protective efficacies of the epitope DNA vaccines in chickens against E.tenella,E.necatrix,E.maxima and E.acervulina were evaluated.The results showed that the constructed multivalent epitope DNA vaccines significantly increased body weight gain,alleviated enteric lesions and reduced oocyst output of the infected birds.Especially,the multivalent epitope DNA vaccines of pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1and pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1-IL-2 not only significantly increased body weight gain,alleviated enteric lesions and reduced oocyst output of the infected birds,but also resulted in anti-coccidial index(ACI)more than 170 against E.tenella,E.necatrix,E.maxima and E.acervulina,which indicated they could induce protective immunity against E.tenella,E.necatrix,E.maxima and E.acervulina.Our findings suggest the constructed multivalent epitope DNA vaccines are the potential candidate multivalent vaccines against mixed infection of Eimeria.