Proteomic analysis of Brucella abortus cell envelope and identification of immunogenic candidate proteins for vaccine development

Brucella abortus is the etiologic agent of bovine brucellosis and causes a chronic disease in humans known as undulant fever. In livestock the disease is characterized by abortion and sterility. Live, attenuated vaccines such as S 19 and RB51 have been used to control the spread of the disease in animals; however, they are considered unsafe for human use and they induce abortion in pregnant cattle. For the development of a safer and equally efficacious vaccine, immunoproteornics was utilized to identify novel candidate proteins from B. abortus cell envelope (CE). A total of 163 proteins were identified using 2-DE with MALDI-TOF MS and LC-MS/ MS. Some of the major protein components include outer-membrane protein (OMP) 25, OMP31, Omp2b porin, and 60 kDa chaperonin GroEL. 2-DE Western blot analyses probed with antiserum from bovine and a human patient infected with Bracella identified several new immunogenic proteins such as fumarate reductase flavoprotein subunit, F0F1-type ATP synthase a subunit, and cysteine synthase A. The elucidation of the immunome of B. abortus CE identified a number of candidate proteins for developing vaccines against Brucella infection in bovine and humans.