Application of proteomics in identifying protective antigens of Streptococcus iniae

in International Symposium (poster paper), 國際研討會(全文海報發表)
標題Application of proteomics in identifying protective antigens of Streptococcus iniae
AuthorsChung-Da Yang, 楊忠達
出版日期Sep 12 2011 12:0

Streptococcus iniae (S. iniae) has become an important aquatic pathogen and has caused serious streptococcosis outbreaks of cultured fish in the world. The infection generates a great economic loss in the aquaculture industry. In the present study, we attempt to screen protective antigens of S. iniae to develop a potent vaccine for managing the infection. First, pulsed-field gel electrophoresis (PFGE) was employed to discriminate the genotypes among S. iniae strains collected in southern Taiwan. Sin-7 and Sin-18 showed very different genotypes and were subjected to a virulence test. Results showed that the virulence of Sin-18 was moderate (25%), whereas that of Sin-7 was high (87.5%). Further, two-dimensional gel electrophoresis (2-DE) consisting of isoelectric focusing (IEF) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to analyze protein lysates from these two isolates. After the image analyses of 2-DE gels, we found that the Sin-7 strain highly expressed 7 proteins and Sin-18 highly expressed 4. The eleven protein spots with significant differences between Sin-7 and Sin-18 strains were then selected for identification by MALDI-TOF mass spectrometry. The proteins were uracil phosphoribosyltransferase, superoxide dismutase, fructose-bisphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), probable catabolite control protein A, UDP-N-acetylglucosamine 1-carboxyvinyltransferase 1, inosine-5'-monophosphate dehydrogenase, phosphate acetyltransferase, a hypothetical protein MG373 homolog, 50S ribosomal protein L10 and glucosamine-fructose-6-phosphate aminotransferase. Among these proteins, we overexpressed one protein, GAPDH, by the E.coli-based expression system. Sera from tilapia infected with S. iniae recognized the purified, recombinant GAPDH protein by immunoblotting assay. This study demonstrates that proteomics can be successfully applied to identify possible vaccine candidates.

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