Variations in antigenicity ofAeromonas hydrophilastrains in rainbow trout (Oncorhynchus mykiss, Walbaum): an association with surface characteristics

Rainbow trout immunised with live cells of Aeromonas hydrophila produced very low antibody titres, i.e. ≤1:6, against one strain (i.e. strain 168) but very high titres (1:5120–1:40 960) against the rough variant of strain 152 (=152r). However, the fish were unable to respond to two other colony variants of strain 152, coined as 152s and 152c. The inter-strain variation in antigenicity corresponded with morphological, serological, surface-associated and biochemical differences. The variation in antigenicity of the three colony forms of strain 152 was related with differences in hydrophobicity, precipitation after boiling, the ability to pellet, and the binding of Coomassie brilliant blue.