The present study was designed to establish transgenic Eimeria mitis (tE. mitis) expressing chicken interleukin-4 (ChIL-4) and further exploitation of tE. mitis as a novel vaccine vector to control coccidiosis. For this purpose we compared the clinico-hematological alterations induced by wild type and tE. mitis carrying ChIL-4 in broilers birds. Wild type E. mitis (wE. mitis) oocysts were nucleofected with double cassette vector and transgenic oocysts were propagated for stable transfection. Stability of the transfected E. mitis was observed by fluorescent microscopy and PCR analysis revealed the appearance of 411bp band suggestive of presence of IL-4 into the genome of tE. mitis. Birds inoculated with transgenic EmiChIL-4 excreted fewer oocysts and fecundity potential of tE. mitis turned out to be significantly lower than that of the wild type parent strain. Moderate clinical and behavioral signs such as restlessness, diarrhea, emaciation, decreased feed intake and loss of body weight was observed in birds inoculated with wE. mitis oocysts. The erythrocyte counts, Hb conc, PCV and MCHC decreased in birds infected with wE. mitis as compared to those infected with tE. mitis. The total leukocyte count including heterophils, eosinophil and basophils increased while lymphocytes were decreased in birds inoculated with wE. mitis as compared to birds in control group and those infected with tE.mitis. It was concluded that tE. mitis incorporated with ChIL-4 functions well as an adjuvant, conferring reduced fertility and compromised pathogenicity of tE. mitis. This discrimination, may be applied as a potential vaccine vector to control coccidiosis as well as pathogens from which antigens are expressed by tE. mitis.

Key words: Birds, Hematology, Interleukin 4, Transgenic E. mitis