Immunization of mice with recombinant S-adenosyl-L-homocysteine hydrolase protein confers protection against Brucella melitensis infection.

Due to drawbacks of live attenuated vaccines, much attention has been focused on screening Brucella-protective antigens as subunit vaccine candidates. Here, an immunoproteomic assay was used to identify the immunogenic soluble proteins of Brucella melitensis 16M. In the present study, 27 unique immunogenic proteins were identified from the two-dimensional electrophoresis immunoblot profiles by liquid chromatography tandem MS (LC-MS/MS). From this set, the gene encoding one immunodominant protein of interest, S-adenosyl-l-homocysteine hydrolase (AdoHcyase), was expressed in Escherichia coli. The recombinant AdoHcyase induced a strong antibody response in BALB/c mice, and the polyclonal antibody could recognize a band of approximately 52 kDa in the immunoblots of soluble protein extracts from five Brucella strains. rAdoHcyase significantly stimulated the production of interferon-γ and interleukin-2, and induced a high level of protection against B. melitensis 16M challenge at 4 weeks postchallenge. Our results indicated that rAdoHcyase could be a useful candidate for the development of subunit vaccines against B. melitensis.