Studies on construction of a recombinant Eimeria tenella SO7 gene expressing Escherichia coli and its protective efficacy against homologous infection

Eimeria spp are the causative agents of coccidiosis a major disease affecting the poultry industry A recombinant non antibiotic Escherichia coli that expresses the Eimeria tenella SO7 gene was constructed and its protective efficacy against homologous infection in chickens was determined The three-day-old chickens were orally immunized with the recombinant non-antibiotic SO7 gene expressing E cob and boosted two weeks later Four weeks after the second immunization the chickens were challenged with 5x10(4) homologous sporulated oocysts The protective effects of the recombinant non antibiotic E colt were determined by measuring body weight change mortality histopathology lesion scores oocyst counts the specific antibody response and the frequency of CD4(+) and CD8(+) lymphocytes in peripheral blood The results showed that immunization with SO7 expressing E colt resulted in significantly improved body weight gain reduced lesion scores and oocyst shedding in immunized chickens compared to controls Furthermore administration of recombinant SO7 expressing E coli leads to a significant increase in serum antibody CD4(+) and CD8+ T cells in peripheral blood of chickens These results therefore suggest that the recombinant non-antibiotic E cob that expresses the SO7 gene is able to effectively stimulate host protective immunity as evidenced by the induction of development of both humoral and cell-mediated immune responses against homologous challenge in chickens (C) 2010 Elsevier Ireland Ltd All rights reserved