To investigate the immunogenicity of reticuloendotheliosis virus(REV) Env protein, in this study, the env gene was cloned into pAO815 vector to construct recombinant plasmid pAO815-2 env containing two env expression cassettes(Bgl Ⅱ and BamH Ⅰ restriction sites in the env gene have been mutated). Then it was transformed into Pichia pastoris strain GS115 by electroporation to construct recombinant P.pastoris strain GS115/pAO815-2 env. The expressed recombinant protein(protein content reaches 4.8 g/L) was pur...