Identification of 62-kDa Protein as an Immunogenic Antigen of Vibrio vulnificus for Humans

[Abstract] Vibrio vulnificus infection can cause necrotizing fasciitis and sepsis and can develop within a few days despite intensive care. The mortality rate is up to 60% in vulnerable people. Most patients infected with this microbe have chronic liver disease, especially liver cirrhosis or cancer, as an underlying disease. V.vulnificus infection is opportunistic, and there is an urgent need to develop an anti-V.vulnificus vaccine. Thus, it is important to identify immunogenic antigens. We collected human sera from three subject groups: patients with V.vulnificus infection, patients with chronic liver disease but without V.vulnificus infection, and healthy volunteers with normal liver function. Immunoblots of cytosolic and membrane proteins of seven strains of V.vulnificus and one of V.parahaemolyticus were performed with sera from these groups. Although we could not demonstrate differences in antibody response between the groups, all sera showed a strong antibody response to a 62-kDa protein that was common to all strains examined. Immunoblots of Escherichia coli and Klebsiella pneumoniae also showed strong antibody response to this 62-kDa protein, and the possibility of cross-reaction cannot be denied. We identified this 62-kDa protein as an immunogenic antigen of V.vulnificus for humans.