Prokaryotic expression and identification of B- and T-cell combined epitopes of Em95 antigen of Echinococcus multilocularis.

Objective: This study is to clone and identify B- and T-cell combined epitopes from Em95 antigen.

Methods: The B- and T-cell combined epitopes were predicted using bioinformatic software. Two DNA sequences of Em95-1 (which contained the coding region of one B- and T-cell combined epitope) and Em95-2 (which contained the coding regions of two B- and T-cell combined epitopes) were amplified by PCR. Em95-1 and Em95-2 were cloned into pET32a vector for protein expression. Rabbit was immunized with the expressed proteins of rEm95-1 and rEm95-2 to produce polyclonal antibodies. The immunogenicity and antigenicity of rEm95-1 and rEm95-2 were examined by Western blot analysis.

Results: The three B- and T-cell combined epitopes were successfully cloned and expressed in PET32a vector. The recombinant antigens of rEm95-1 and rEm95-2 could specifically bind the human serum from patients with alveolar echinococcosis and specifically bind the prepared polyclonal antibodies.

Conclusion: Three B- and T-cell combined epitopes were successfully cloned with good immunogenicity and antigenicity. Our data suggest that B- and T-cell combined epitopes predicted from the Em95 antigen may be used for the construction of high-valence vaccines and as targets for prevention of echinococcosis.