Production of proteinase during experimental infection of Ostrea edulis L. larvae with Vibrio alginolyticus NCMB 1339 and the antigenic relationship between proteinases produced by marine vibrios pathogenic for fish and shellfish

Abstract. Seven marine Vibrio strains pathogenic for fish or shellfish (including strains of Vibrio alginolyticus, V. anguillarum, V. tubiashi and V. ordalii ) were categorized into three groups on the basis of their extracellular proteinases. Antiserum raised against purified Vibrio alginolyticus NCMB 1339 proteinase neutralized the enzymes produced by all seven Vibrio strains and, on immunodiffusion, the V. alginolyticus proteinase gave a reaction of partial antigenic identity with the other Vibrio strains. In experimental infections of Ostrea edulis larvae with V. alginolyticus , the production of proteinase was demonstrated by immunofluorescence with fluorescein-labelled anti-serum. The toxicity of purified proteinase to larval O. edulis was significantly reduced by preincubation with antiserum but, when larvae were challenged with V. alginolyticus culture supernate containing a similar proteinase concentration, preincubation with antiserum had no protective effect.