In ovo vaccination with the Eimeria tenella EtMIC2 gene induces protective immunity against coccidiosis.

An Eimeria tenella microneme recombinant gene (EtMIC2) and encoded protein were evaluated as potential vaccines against avian coccidiosis. In ovo inoculation with the EtMIC2 gene increased anti-EtMIC2 antibody titers at days 10 and 17 following E. tenella infection. In addition, vaccinated birds developed protective immunity against infection by E. tenella as assessed by significantly increased body weight gain and decreased fecal oocyst shedding compared with non-vaccinated controls. Vaccination with the EtMIC2 gene also led to protective immunity against infection by E. acervulina, but not E. maxima. Combined in ovo DNA vaccination plus post-hatch boosting with EtMIC2 DNA or protein did not improve antibody titers or protective immunity beyond that achieved with in ovo vaccination alone. These results provide evidence that in ovo immunization with a recombinant Eimeria microneme gene stimulates protective intestinal immunity against coccidiosis.