Immunoproteome analysis of soluble and membrane proteins of Shigella flexneri 2457T

Aim: To profile the immunogenic proteins of Shigella flexneri (S. flexneri) expressed during human infection using a proteomic approach. Methods: Soluble and membrane protein extractions of S. flexneri 2457T were separated by two-dimensional gel electrophoresis (2-DE). Proteins were transferred to PVDF membrane and immunoblotted with sera from shigellosis patients. Reactive protein spots were matched to Coomassie stained gels run in parallel, cut out and trypsin digested. Matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS) was used to determine the peptide mass fingerprints, which were searched in the MASCOT database to identify the protein. Results: A total of 8 immunoreactive proteins were successfully identified from the Coomassie stained gels in three repeats. Six of these proteins have not previously been reported as immunogenic in S. flexneri. These proteins could be potential candidates for vaccine or attenuation studies. Conclusion: Soluble and membrane proteins of S. flexneri 2457T have been screened by 2-DE and immunoblotting with sera from shigellosis patients. Eight proteins are identified as immunogenic.