Comparison of receptor-binding properties among influenza C virus isolates

A total of 10 influenza C virus strains isolated recently in Yamagata City, Japan and shown to belong to the same lineage was compared for the ability to agglutinate chicken and mouse erythrocytes under various conditions. C/Yamagata/10/89 was unique in lacking the ability to agglutinate chicken erythrocytes at a temperature greater-or-equal, slanted 4°C. This isolate also agglutinated native mouse erythrocytes only very inefficiently, although the high agglutination titer was obtained with the glutaraldehyde-fixed cells. Furthermore, it was found that C/Yamagata/4/88, unlike the other isolates, agglutinated erythrocytes from chickens to lower titers than those from mice, even when assayed at 0°C. Comparison of the deduced amino acid sequence of hemagglutinin-esterase among the 6 representative strains including two older isolates, C/Yamagata/26/81 and C/Nara/2/85, suggested that the failures of C/Yamagata/10/89 to agglutinate chicken erythrocytes at greater-or-equal, slanted 4°C and unfixed mouse erythrocytes to high titers may be due to amino acid changes at residues 337 (Glu → Lys) and 340 (Thr → Tyr), respectively, and that a change at residue 347 (Leu → Ser) may be responsible for the decreased ability of C/Yamagata/4/88 to agglutinate chicken erythrocytes.