Putative periplasmic

binding protein CbiK is involved in the uptake of Ni2+, a cofactor required for urease activity that is important in pathogenesis of pleuropneumonia [44]. The ilv gene of Brucella suis has been identified as a virulence gene[45], and its product, acetohydroxyacid synthase, catalyzes the first common step in the biosynthetic pathway of the branched-amino acids such as leucine, isoleucine, and valine. Iron is essential for bacterial growth, especially for A. pleuropneumoniae in invading and reproducing in porcine respiratory tract where iron is limited. Iron-restriction is an important signal that regulates expression of many genes including some coding for virulence factors[46]. FepB, AfuC and FatB are components of known iron transport pathways, and the immunogenic reactivity of these proteins in this study indicates that these iron-uptake proteins might be potential candidates Neratinib for development of subunit vaccines. Wnt drug D-Galactose/D-glucose binding protein (GGBP) is a bacterial periplasmic protein, an initial component for both chemotaxis towards galactose and glucose and active transport of the two sugars in Escherichia coli[47]. The crystal structure of uroporphyrinogen-III methylase (CysG) from Thermus thermophilus has been reported[48] and the cysG gene of Salmonella typhimurium is involved in synthesis of both cobalamin (B12) and siroheme[49]. The ttg2D gene encodes a periplasmic component of an ABC-type transport system related to

resistance to organic solvents, and Ttg proteins of Pseudomonas putida and N. meningitidis were verified to participate in the uptake of L-glutamate[50]. Novel vaccine candidates need to be highly conserved between strains and so that they induce cross-protection against A. pleuropneumoniae. Recently Goure et al. have identified

A. pleuropneumoniae Dapagliflozin genes that are conserved among all 15 serotypes by comparative genomic hybridization[51]. Of these conserved genes, the genes encoding proteins MomP1 (OMP P5), MomP2 (OMP P5), D15 (OmpD), LppB, PotD, FkbP and FrpB were observed in our results. Besides, NqrA has been demonstrated to be common to all serotypes[15]. Thus these conserved proteins could potentially induce protection against a wide variety of strains and are attractive vaccine candidates. Conclusion In conclusion, the 2DE in combination with Western blot is a specific and powerful method to discover novel antigens from bacterial pathogens. In this study, the identified immunogenic proteins from ECPs and OMPs may be significant for the development of new efficient vaccine against A. pleuropneumoniae. The protective efficacy of the identified immunogenic proteins either by alone or in different combinations remains to be evaluated in further studies. The data of this study are expected to aid in development of novel vaccines against A. pleuropneumoniae. The present study has focused on 2DE analysis coupled with Western blotting. Methods Bacterial strains and culture conditions A.