Abstract: Objective To increase yield expression of Ts87 gene was optimized in P.pastoris from the aspects,such as vector construction,to obtain multicopy transformants and inductive conditions.Methods Signal sequences of Ts87 gene was deleted and the recombinant vector was constructed with nature N end,then used X-33 host cell dealt with LiCl before electroporation to get a appropriate conditions from cell densities,methanol concentration,pH and induction time,etc.The expression product was analyzed by Western blotting.Results The efficiency of electroporation increased by the method which prepared host cell with LiCl and the appropriate inductive conditions were OD_{600 nm}=1.0,1.0%/24 h methanol added,pH=7.0 or 8.0,72 h.The expression protein was detected as positive reaction with infected rabbit sera when tested directly with 30 μL supernatant.Conclusion The appropriate condition for Ts87 gene in P.pastoris expression system is obtained.

Key words: Trichinella spirialis, Pichia pastoris, Ts87, expression