Evidence from studies with a cross-linking reagent that the haemagglutinin of influenza virus is a trimer

Influenza haemagglutinin in situ on the virus membrane, isolated by detergent solubilization and isolated by bromelain treatment, has been chemically cross-linked with dimethyl suberimidate. The results demonstrate that the haemagglutinin is a trimer of the HA1 and HA2 subunit in all cases.