Characterization of hemagglutinins in various fimbrial types of Prevotella intermedia

Abstract

     We examined hemagglutination activities of various fimbrial types of Prevotella intermedia and characterized the hemagglutinins.
     Almost all strains tested possessed agglutinating activity with rabbit erythrocytes. No relationship between hemagglutination activity and DNA homology group or fimbrial type was recognized. All strains with no fimbriae showed a wide range of hemagglutinating activities (from titer 2 to 32). All strains except two lost activities after heat treatment at 70°C for 10 min. Hemagglutination activity of the remaining two strains was eliminated after exposure to heat at 100°C for 10 min. Trypsin, chymotrypsin, protease and lysozyme either eliminated or reduced the hemagglutination activities of 14, 13, 12 and 5 strains, respectively, of the 18 examined. However, β-glucosidase and β-galactosidase did not affect hemagglutination activity in any of the strains. Of 17 sugars tested, only D-glucosamine caused hemagglutination inhibition of Prevotella intermedia, and this was in only one strain, E8, which was in the ATCC 33563 group.
     Morphological changes in the cell surface of strain O2, which was D-glucosamine-resistant, trypsin-sensitive and carrying type A fimbriae, were studied after treatment with trypsin. With negative staining, trypsin-treated cells lacked the folds characterizing gram-negative bacteria. However, type A fimbriae still remained after treatment with trypsin. In thin-sectioned micrographs, treated cells partially lost the dense outer membrane layer. In SDS-PAGE, trypsin-treated cells lacked a protein of about 27 kDa compared with untreated cells, suggesting that hemagglutination of that O2 strain may result from this protein on the outer membrane, but not from type A fimbriae.
     These results and previous data indicate that there are many types of hemagglutinins on Prevotella intermedia.