[Variation of influenza viruses and their recognition of the receptor sialo-sugar chains]

Influenza A, B viruses contain 2 viral specific, membrane associated glycoprotein antigens, hemagglutinin and sialidase. Hemagglutinin is essential for the initial binding of the virus to the cell membrane receptors that contain sialic acid such as gangliosides and sialo-glycoproteins. Hemagglutinin is also important for the intracellular viral uncoating by the low pH fusion processes. The evolution of the influenza viruses and host range variation come from the mutation of hemagglutinin and sialidase genes and change of their sialo-sugar chain recognition together with alteration in the antigenic epitopes. In this report, the molecular mechanism of the relationship between the evolutional change of the viral glycoproteins, especially hemagglutinin molecules and the change of the receptor binding specificity is reported, and also the strategy for the development of a new universal vaccine which generates the antibody whose supervariable region mimics the common receptor sialo-sugar chains for all the subtypes of influenza viruses is also described.