Surface layer virulence A-proteins from Aeromonas salmonicida strains.

Superficial surface layer proteins (A-proteins) were present on diverse isolates of Aeromonas salmonicida which differed both physiologically and in pathogenesis. Three of these proteins were purified directly from the surface of whole cells or from outer membrane preparations. These A-proteins were unusually hydrophobic (45-47%) and of similar but not identical molecular mass (49, 50, and 51 kdaltons). They were nearly identical in amino acid composition and were highly conserved, but not identical with respect to their hydrophobic N-terminal amino acid sequences. These proteins differed, however, with respect to their oligomerization properties, isoelectric forms, and chymotryptic peptide patterns. All three proteins were immunologically closely related and shared surface-exposed immunoreactive peptides with 28 separate isolates.