Comparative Proteomics Assay Of Extracellular Proteins Of Aeromonas Hydrophila Strain J-1in Different Culture Conditions

With the wide existence in tne nature world, Aeromonas hydrophila （Ah） is a kind of aquatic animal pathogen, which can cause fatal hemorrhagic septicemia in fish, and leads great economic damage to the aquaculture. Besides, it is the important pathogen of zoonosis, extremely harming the health of human beings. Nowadays the killed whole-cell vaccines and the living vaccines both have severe defects, as a result, the development of subunit vaccines become more and more crucial.For the pathogen, the extracellular proteins are very important, which can secrete into the extracellular acting on the host’s immune system, and induce immune protection force. In this research, comparative proteomics analysis was chosen to evaluate the differences between2-D gel profiles of extracellular proteins of Aeromonas hydrophila strain J-1cultivated at different temperature.By2-D gel electrophoresis, the expression profiles of extracellular proteins of Aeromonas hydrophila strain J-1cultivated at28℃and37℃were obtained, and then the differential protein spots were found. By MALDI-TOF-MS and database searches, eight differential protein spots were successfully identified, including serine protease, hemolysin, elongation factor Tu, galactose ABC transporter, major outer membrane protein, hypothetical protein AHA₀616, pro aerolysin. Meanwhile, two of these proteins were temperature up-regulation proteins, and the other six were temperature down-regulation proteins.In order to analyse the differential proteins of extracellular proteins at the certain temperature between logarithmic phase and stationary phase, the2-D gel profiles of Aeromonas hydrophila strain J-l cultivated for8h or14h at28℃and37℃were compared respectively. Seven differential proteins cultivated at28℃and three differential proteins cultivated at37℃were identified, including serine protease, extracellular protease, nuclease, D-ribose transporter subunit RbsB, hemolysin and hypothetical protein AHA₀616. Analysing by the on-line software SignalP3.0for signal peptide prediction, the result showed that all the differential proteins contained typical signal peptide structure. That meant, from the bioinformatics perspective, the nine proteins indentified were extracellular proteins.The differential proteins indentified in this experiment, such as aerolysin, hemolysin, major outer membrane protein and extracellular protease, all had immunogenicity, and could be used in production of subunit vaccines. This study proved that the expression of extracellular proteins of Aeromonas hydrophila strain J-1could be regulated by culture temperature and different stages of growth and reproduction, which could provide theory evidences for optimizing the condition of vaccine production by controlling the culture temperature and time in the future.