Myxoviruses (influenza viruses and paramyxoviruses) penetrate their host cells by fusion of viral and cellular membranes. During this process, virus envelopes react with galactose-terminating glycolipids of cellular membranes. This was suggested by experiments showing the ability of these lipids to inhibit fusion (as measured by haemolysis) when reacted with the viruses, and to enhance it when added as enrichment to erythrocytes.