Study on the immunogenicity of synthetic polypeptide vaccine derived from Theileria sergenti merozoite

Theileria sergenti merozoite의 합성 polypeptide 백신의 면역원성에 관한 연구

Western immunoblot analysis of antigen of T sergenti merozoite revealed that the immunodominant proteins of this organism were characterized as the 18KD, 29KD, 34KD, 45KD and 105KD in Korea. The 34KD and 45KD among those immunodominant proteins of the parasite were isolated and their amino acid sequences from the $NH_2$-terminus were determined and synthesized. They respective polypeptides were cationized to enhance their antigenicity, fortified with Freund's adjuvant and tested for immunogenicity in rabbits and cattle. The results obtained were as follows; 1. Theileria sergenti merozoite antigen was shown in 120KD, 100KD, 66KD, 45KD, 34KD and 30KD in western immunoblot using serum of rabbits immunized with 34KD synthetic polypeptide and 70KD, 58KD, 55KD and 45KD using bovine serum. In western immunoblot, 45KD, 34KD and 30KD were recognized by immunized rabbits, and 50KD and 45KD by cattle sera immunized with 45KD synthetic polypeptide, respectively. 2. The ELISA utilizing the synthetic polypeptides demonstrated significant antibody response to the respective peptides. After the 2nd booster injection, an OD of 0.760(preimmunization 0.132) in rabbits and an OD of 0.645(preimmunization 0.488) to 34KD synthetic polypeptide in cattle were observed. In animals immunized with 45KD synthetic polypeptide, after the 2nd booster injection, an OD of 0.640(preimmunization 0.144) in rabbit, and an OD of 0.776 (preimmunization 0.477) in cattle were measured. 3. After the 2nd booster the reciprocal IFA titer was 1:64 in rabbits and 1:512 in cattle immunized with the 34KD synthetic polypeptide. The IFA titre was observed as 1:512 in rabbit and 1:1,024 in cattle in immunized with the 45KD synthetic polypeptide.