A galactose-binding protein revealed as a hemagglutinin in Aphanomyces piscicida

Abstract

Aphanomyces piscicida is a water mold that is pathogenic to several species of fish. Here we describe that a galactose-binding protein (GBP) purified from A. piscicida has a hemagglutinating activity. The GBP was separated from the supernatant of homogenized hyphae of A. piscicida by affinity chromatography using an immobilized D-galactose agarose gel. The GBP agglutinated goldfish erythrocytes. The molecular weight of the GBP was estimated at approximately 40 kDa by SDS-PAGE. A specific antiserum was produced against the GBP and the 40 kDa protein reacting with the antiserum was observed in only Aphanomyces strains isolated from diseased fish. These results suggest that the 40 kDa GBP is closely associated with Aphanomyces infections, such as mycotic granulomatosis, epizootic ulcerative syndrome, red spot disease and ulcerative mycosis.