The receptor-destroying enzyme of influenza C virus is neuraminate-O-acetylesterase.

Abstract

The nature of the receptor‐destroying enzyme (RDE) of influenza C virus has been elucidated by analyzing its effect on the haemagglutination inhibitors rat alpha 1‐macroglobulin (RMG) and bovine submandibulary mucin (BSM), respectively. The inhibitory activity of both compounds is abolished by incubation with influenza C virus. After inactivation, RMG and BSM were found to contain reduced amounts of N‐acetyl‐9‐O‐acetylneuraminic acid (Neu5,9Ac2) and increased amounts of N‐acetylneuraminic acid (Neu5Ac). H.p.l.c. analysis revealed that purified Neu5,9Ac2 is converted to Neu5Ac by incubation with influenza C virus. These results demonstrate that RDE of influenza C virus is neuraminate‐O‐acetylesterase [N‐acyl‐9(4)‐O‐acetylneuraminate O‐acetylhydrolase (EC 3.1.1.53)]. The data also indicate that haemagglutination‐inhibition (HI) by RMG and BSM and most likely virus attachment to cell surfaces involves binding of influenza C virus to Neu5,9Ac2.