The Construction Of CDNA Expression Library Of Eimeria Tenella And Screening, Cloning & Expression Of Major Immunogen Gene

The Phylum Apicomplexa is composed entirely of parasitic protists, including many pathogens of veterinary and medical importance (e.g., Eimeria, Plasmodium, Babesia, Toxoplasma, Cryptosporidium and Sarcocystis). Among various parasitic infections, coccidiosis caused by obligate intracellular protozoan parasite of the genus Eimeria is the major constraint for modern poultry production. Coccidiosis, caused by various Eimeria spp., not only threatens the health and welfare of poultries, but also causes significant economic losses in poultry industries around the world. Among various Eimeria spp., Eimeria tenella, which causes caecal coccidiosis, is highly pathogenic. In spite of advances in immunological, biotechnological and genetical methods, control of coccidiosis chiefly depends upon prophylactic chemotherapy with anticoccidial drugs. However, the emergence of drug resistance in coccidia is a great problem with most of the drugs, which, in due course, limits their use. Furthermore, drug- or antibiotic-residue in the poultry product is potentially harmful to consumers. These limitations have necessitated the search for alternative Eimeria control measures. Among the several alternative Eimeria control measures only host vaccination against Eimeria appears promising. In this research, our strategy was constructing the cDNA expression library of the sporozoites by Eimeria tenella sporulated oocysts, and screening, cloning the immunogen genes, as well as expressing the interesting genes, analysing the protective immunity. Results of studies displayed as following.1. Chickens was orally infected with sporulated oocysts of E. tenella YL strain for preparations of anti-E. tenella YL strain positive serum. Rabbit was infected with sporulated oocysts of E. tenella YL strain for preparations of anti-E. tenella YL strain positive serum. The results showed that two kinds of positive sera could be use for immunoscreening from cDNA expression library.2. We first constructed successfully cDNA expression library of the E. tenella sporozoites by sporulated oocysts of E. tenella YL strain. The results showed that the transformation efficacy of library was 4×106 pfu/mL. We cloned the surface antigen 3-1E...