Biosynthetic modulation of sialic acid-dependent virus-receptor interactions of two primate polyoma viruses.

Sialic acids are essential components of the cell surface receptors of many microorganisms including viruses. A synthetic, N-substituted D-mannosamine derivative has been shown to act as precursor for structurally altered sialic acid incorporated into glycoconjugates in vivo (Kayser, H., Zeitler, R., Kannicht, C., Grunow, D., Nuck, R., and Reutter, W. (1992) J. Biol. Chem. 267, 16934-16938). In this study we have analyzed the potential of three different sialic acid precursor analogues to modulate sialic acid-dependent virus receptor function on different cells. We show that treatment with these D-mannosamine derivatives can result in the structural modification of about 50% of total cellular sialic acid content. Treatment interfered drastically and specifically with sialic acid-dependent infection of two distinct primate polyoma viruses. Both inhibition (over 95%) and enhancement (up to 7-fold) of virus binding and infection were observed depending on the N-acyl substitution at the C-5 position of sialic acid. These effects were attributed to the synthesis of metabolically modified, sialylated virus receptors, carrying elongated N-acyl groups, with altered binding affinities for virus particles. Thus, the principle of biosynthetic modification of sialic acid by application of appropriate sialic acid precursors to tissue culture or in vivo offers new means to specifically influence sialic acid-dependent ligand-receptor interactions and could be a potent tool to further clarify the biological functions of sialic acid, in particular its N-acyl side chain.