Abstract: Glutamate dehydrogenase (GDH) which exists in 35 serotypes of Streptococcus suis,is an immunogenic protective antigen.Therefore,the GDH gene was amplified by PCR method,and the GDH gene PCR fragment was inserted oriented to pET-32a to construct a new recombinant expression vector pET-32a-GDH.The E.coli BL21(DE3)(pET-32a-GDH) was cultured and induced to express the rGDH protein.New Zealand White rabbits were immunized by the purified rGDH protein for immunity protective test to determine the immunogenicity of the protein.The results showed that the recombinant expression vector pET-32a-GDH was successfully constructed,and the rGDH protein was efficiently and solubly expressed.70% of model animals immuned by the rGDH protein with propolis as adjuvant were protected after injection of Streptococcus suis type 2 as a virulent pathogen.The experiment results provided technical support for the development of subunit vaccine of Streptococcus suis.

Key words: Streptococcus suis; glutamate dehydrogenase (GDH); prokaryotic expression; immunogenicity