Journal of Clinical and Cellular Immunology
Open Access
ISSN: 2155-9899
ISSN: 2155-9899
Miao Dong
City University of Hong Kong, Hong Kong
Posters & Accepted Abstracts: J Clin Cell Immunol
The objectives of this study are to systematically characterize the serum proteins from fish that stably bind to bacteria and to investigate how bacteria respond to these interactions. Serum from turbot, but not the heat inactivated control, significantly decreased the number of viable E. tarda bacteria. By conjugating fish serum proteins with fluorescent dyes, we showed that E. tarda were coated with multiple labeled proteins before lysis. In order to systematically identify these bacteria binding proteins, we used living E. tarda cells to capture turbot serum proteins and subjected the samples to shotgun proteomic analysis, followed by label-free quantitation. A total of 76 fish proteins have been identified, including known antimicrobial proteins such as immunoglobins, plasminogen, complement components and Wap65-2.34 proteins with no previously known immunological function were also identified to bind to E. tarda. This approach also allowed the study of the proteomic changes in E. tarda exposed to turbot serum. Our data indicated a rapid decrease of translation factors and an up regulation of membrane components in response to serum treatment. Interestingly, fish serum induced a rapid suppression of the expression of bacterial antioxidant enzymes like catalase and led to an accumulation of reactive oxygen species, suggesting that fish serum can override a bacterial self defense mechanism. Taken together, this work offers a comprehensive view of the interactions between fish serum proteins and pathogenic bacteria and reveals previously unknown factors and mechanisms in fish innate immunity.