Hemagglutinating and hemolytic capacities of Aphanomyces piscicida

This study demonstrates that the fish pathogenic Aphanomyces piscicida (= A. invadans) possesses hemagglutinating and hemolytic activities. These activities were observed against goldfish erythrocytes using supernatant of the homogenized hyphae of A. piscicida. The hemagglutinating activity was not inactivated by heat treatment at 60 degrees C for 30 min or by the addition of EDTA. D-galactose or lactose inhibited the hemagglutinating activity. D-galactose-binding substances which were isolated by affinity chromatography showed hemagglutinating activity. On the other hand, heat treatment at 60 degrees C for 30 min reduced the hemolytic activity. It was demonstrated that a sample that did not absorb to D-galactose in affinity chromatography was responsible for the hemolysis. The factors that have hemagglutinating and hemolytic capacities may affect the blood cells of infected fish in vivo, and may play a role in the occurrence of anemia in infected fish.