Enhanced immunogenicity of Renibacterium salmoninarum in chinook salmon after removal of the bacterial cell surface-associated 57 kDa protein

A study was conducted to determine the effect of endogenous senne protease activity on the immunogenicity of Renibactellurn salmonlnarum cells in chinook salmon Oncorhynchus tshawytscha Salmon were immunized with either R salrnon~narum cells possessing p57 (p57') or substantially depleted of p57 ( ~5 7 -) The resultant antisera were examined by whole cell ELISA and immunoblot procedures using p57+, p57-, proteinase-K-treated, and penodate-treated whole cells These analyses revealed that the removal of p57 by the endogenous senne protease significantly enhanced the immunogenlcity of the cell, resulting in a 20-fold increase in detectable antibody titers The bulk of this antibody activity was directed at sites blocked by the presence of the p57 molecule Furthermore, proteinase-K and penodate treatment of R salmonlnarum cells revealed that the increased antibody activity almost exclusively reacted with carbohydrate moieties on the p57-cell