%0 Journal Article %T Use of in vivo-induced antigen technology (IVIAT) for the identification of Streptococcus suis serotype 2 in vivo-induced bacterial protein antigens %A Hongwei Gu %A Haodan Zhu %A Chengping Lu %J BMC Microbiology %D 2009 %I BioMed Central %R 10.1186/1471-2180-9-201 %X Convalescent-phase sera from pigs infected with SS2 were pooled, adsorbed against in vitro antigens, and used to screen SS2 genomic expression libraries. Upon analysis of the identified proteins, we were able to assign a putative function to 40 of the 48 proteins. These included proteins implicated in cell envelope structure, regulation, molecule synthesis, substance and energy metabolism, transport, translation, and those with unknown functions. The in vivo-induced changes in the expression of 10 of these 40 genes were measured using real-time reverse transcription (RT)-PCR, revealing that the expression of 6 of the 10 genes was upregulated in the in vivo condition. The strain distribution of these 10 genes was analyzed by PCR, and they were found in the most virulent SS2 strains. In addition, protein sequence alignments of the newly identified proteins demonstrate that three are putative virulence-associated proteins.Collectively, our results suggest that these in vivo-induced or upregulated genes may contribute to SS2 disease development. We hypothesize that the identification of factors specifically induced or upregulated during SS2 infection will aid in our understanding of SS2 pathogenesis and may contribute to the control SS2 outbreaks. In addition, the proteins identified using IVIAT may be useful potential vaccine candidates or virulence markers.Streptococcus suis (S. suis) infections have been considered a major problem in the swine industry worldwide, particularly over the past 20 years. S. suis is a gram-positive, facultatively anaerobic coccus, and 35 serotypes (1-34 and 1/2) have been described based on their capsular antigens. Among these, serotype 2 (SS2) is the causative agent of many different syndromes worldwide, including meningitis, septicemia, arthritis, and pneumonia in humans, swine, and other animals [1]. In addition, SS2 is widely recognized as an important zoonotic agent that afflicts people in close contact with infected pigs or pork-deri %U http://www.biomedcentral.com/1471-2180/9/201