Study On The Expression Of Recombinant3-1E Protein And Its Protective Immunity Against Eimeria Acervulina

Coccidiosis causes huge economic losses in the poultry industry. At present, the poultry industry largely depends on the anticoccidial drugs to prevent coccidiosis outbreaks. Prophylactic medication is relatively successful in controlling avian coccidiosis in commercial production facilities, but alternative strategies are needed due to the emergence of drug-resistant parasites and increasing government regulations on the use of anticoccidial drugs. With the development of biological technology, gene engineering subunit vaccine has been paid more and more attention. Good subunit vaccines not only need good antigen, but also need the combination of adjuvant to enhance the immune effect. Immune stimulating complexes (ISCOMs), a new kind of antigen presentation system, could enhance the immune function and has double functions of adjuvant and antigen presentation. AbISCO(?)-300is produced from purified saponin, cholesterol and phosphatidyl choline. In this experiment, we select Eimeria acervulina3-1E gene, using Escherichia coli expression system and Pichia pastoris expression system to express the recombinant3-1E protein as antigen, respectively. The gene engineering subunit vaccine, made of the recombinant3-1E protein and ISCOM adjuvant (AbISCO(?)-300), was evaluated its immunological effect.The recombinant3-1E protein was expressed using the Escherichia coli expression system at a low temperature (16℃), then the protein was purified. Chickens were immunized with recombinant3-1E protein in combination with AbISCO(?)-300or recombinant3-1E protein alone. The protective immunity was assessed with body weight gain, fecal oocyst output, detection of intestinal IgA positive cells and percentages of CD3+, CD4+or CD8+intestinal intraepithelial lymphocytes (IELs). Chickens vaccinated with3-lE recombinant protein plus AbISCO(?)-300showed higher percentages of CD3+, CD4+, and CD8+intestinal IELs, increased positive expression rate of intestinal IgA antibody, increased body weight gains and decreased oocyst shedding compared with3-1E recombinant protein-only vaccinated group. The results showed that AbISCO(?)-300enhanced protective immunity elicited by E. acervulina antigen3-1E recombinant protein against avian coccidiosis.The recombinant3-IE protein was expressed using the Pichiapastoris expression system, then the protein was purified. Chickens were immunized with3-1E recombinant protein in combination with AbISCO(?)-300or3-1E recombinant protein alone by ocular and nasal or intramuscular injection respectively. The protective immunity was assessed with body weight gain, fecal oocyst output, detection of intestinal IgA positive cells and percentages of CD3+, CD4+or CD8+intestinal intraepithelial lymphocytes (IELs). Chickens vaccinated by ocular and nasal showed higher percentages of CD3+, CD4+, and CD8+intestinal IELs, increased positive expression rate of intestinal IgA antibody, increased body weight gains and decreased oocyst shedding compared with groups vaccinated by intramuscular injection.