Our previous study demonstrated that chickens immunized subcutaneously with an Eimeria recombinant
profilin protein vaccine emulsified in a
Quil A/
cholesterol/
DDA/
Carbopol (QCDC) adjuvant developed partial protection against experimental avian
coccidiosis compared with animals immunized with
profilin alone. Because in ovo vaccination is presently used in commercial applications worldwide throughout the poultry industry, the current study was undertaken to investigate chicken embryo vaccination with
profilin plus QCDC adjuvant. Eighteen day-old embryos were immunized with isotonic saline (control),
profilin alone, QCDC alone, or
profilin plus QCDC, and orally challenged with live Eimeria maxima at 7 days post-hatch.
Body weight gain, fecal oocyst output, and intestinal
cytokine transcript levels were assessed as measures of protective immunity. While immunization with
profilin alone or QCDC alone did not alter
body weight gain of infected chickens compared with the saline control group, vaccination with
profilin plus QCDC increased
body weight gain such that it was equal to the uninfected controls. Immunization with
profilin plus QCDC also reduced fecal oocyst shedding compared with unimmunized controls, although in this case QCDC failed to provide an adjuvant effect since no difference was observed between the
profilin-only and
profilin/QCDC groups. Finally, increased levels of transcripts encoding IL-1β,
IL-15, and IFN-γ were seen in the intestinal tissues of animals given
profilin plus QCDC compared with the
profilin-only or QCDC-only groups. In summary, this study demonstrates an adjuvant effect of QCDC on
body weight gain and intestinal
cytokine responses following in ovo vaccination of chickens with an Eimeria
profilin vaccine.