Protective immunity induced by Eimeria common antigen 14-3-3 against Eimeria tenella, Eimeria acervulina and Eimeria...

Avian coccidiosis is often caused by co-infection with several species of Eimeria worldwide. Developing a multivalent vaccine with an antigen common to multiple Eimeria species is a promising strategy for controlling clinical common co-infection of Eimeria. In the previous study, 14-3-3 was identified as one of the immunogenic common antigen in E. tenella, E. acervulina and E. maxima. The aim of the present study was to evaluate the immunogenicity and protective efficacy of Ea14-3-3 in the form of DNA vaccine against infection with three species of Eimeria both individually and simultaneously.

After vaccination with pVAX-Ea14-3-3, the Ea14-3-3 gene was transcribed and expressed in the injected muscles. Vaccination with pVAX-Ea14-3-3 significantly increased the proportion of CD4⁺ and CD8⁺ T lymphocytes and produced a strong IgY response in immunized chickens. Similarly, pVAX-Ea14-3-3 stimulated the chicken's splenocytes to produce high levels of Th1-type (IFN-γ, IL-2) and Th2-type (IL-4) cytokines. The vaccine-induced immune response was responsible to increase weight gain, decreased the oocyst output, and alleviated enteric lesions significantly in immunized chickens as compared to control group, in addition to induce moderate anti-coccidial index (ACI).

These results indicate that Ea14-3-3 is highly immunogenic and capable to induce significant immune responses. Furthermore, Ea14-3-3 antigen can provide effective protection against infection with Eimeria tenella, Eimeria acervulina, Eimeria maxima both individually and in combination with three Eimeria species. Significant outcomes of our study provide an effective candidate antigen for developing a multivalent Eimeria vaccine against mixed infection with various Eimeria species under natural conditions.