Selection of influenza virus variants based on sialyloligosaccharide receptor specificity

Influenza viruses bind to host cells by attachment to sialic acid containing oligosaccharides on cell surface glycoproteins and glycolipids. We have examined the receptor specificity of influenza viruses using an approach employing highly purified mammalian sialyltransferases. In conjunction with bacterial sialidases these specific enzymes are used to modify erythrocytes or tissue culture cells to contain a single sialyloligosaccharide receptor determinant of defined sequence. By analysis of viral binding to or infection of the derivatized cells, the receptor specificity of the virus can be deduced. Influenza viruses may exhibit strict and varied receptor binding properties. Although the biological significance of receptor specificity in influenza viruses is not fully understood, host species of influenza may exert selective pressures resulting in the emergence of a receptor variant with properties optimal for growth in that host. The nature of such selective pressures and the selection of receptor binding variants in vitro is discussed.