ABSTRACT
Anticoccidial vaccines comprising living oocysts of Eimeria tenella, Eimeria necatrix, Eimeria maxima, and Eimeria acervulina are used to control coccidiosis. This study explored the potential of IL-1ß to act as a molecular adjuvant for enhancing the immunogenicity of Eimeria necatrix and mucosal immunity. We engineered E. necatrix to express a functional chIL-1ß (EnIL-1ß) and immunized chickens with oocysts of the wild type (EnWT) and tranegenic (EnIL-1ß) strains, respectively. The chickens were then challenged with EnWT oocysts to examine the immunogenicity-enhancing potential of chIL-1ß. As expected, the oocyst output of EnIL-1ß-immunized chickens was significantly reduced compared to those immunized using EnWT. No difference in body weight gain and lesion scores of EnIL-1ß and EnWT groups was observed. The parasite load in the small intestine and caeca showed that the invasion and replication of EnIL-1ß was not affected. However, the markers of immunogenicity and mucosal barrier, Claudin-1 and avian ß-defensin-1, were elevated in EnIL-1ß-infected chickens. Ectopic expression of chIL-1ß in E. necatrix thus appears to improve its immunogenicity and mucosal immunity, without increasing pathogenicity. Our findings support chIL-1ß as a candidate for development of effective live-oocyst-based anticoccidial vaccines.