[Construction and immunogenicity of hCG chimeric peptides (CP1 and CP10) containing three self- B cell epitopes and...

Two bio-synthesizing chimeric peptide (CP) immunogens named CP1 and CP10 have been designed, which consist of three linear B cell epitopes (BCE) of human chorionic gonadotropin beta subunit (beta-hCG) and six foreign T cell epitopes including two "promiscuous" TCEs from hepatitis B surface antigen and tetanus toxoid. Two artificial genes encoding CP1 and its derivative CP10 were synthesized, which could be expressed in E. coli at the level of about 1% of the total cell proteins when inserted into the thermo-induction vector respectively. In Western blot tests, the expressed CP1 and CP10 proteins with about 16.5 kD shown on the SDS-polyacrylamide gel electrophoresis (PAGE) gel can be recognized by the monoclonal or polyclonal antibodies specific to each linear epitope of beta-hCG. Each of expressed proteins can be purified with 95% relative homogeneity using our improved method of preparative gel PAGE. Their yields were about 1-2 mg per 12 L culture. Also, the CPl and CP10 immunogens can induce antibodies in mice that recognize recombinant CP1 betar CP10 and natural beta-hCG, and there are three anti-beta5, beta9 and beta8 BCE antibodies in their antisera. The construction and expression of beta-hCG CP1 and CP10 will provide new immunogens for developing an ideal and superior hCG birth control and/or tumor therapeutic vaccine.