Change in Virus Proteins and Virion Structure on Binding Antibody, Including Synergistic Neutralization
By analogy with interactions involving other macromolecules and their ligands it is possible that binding of antibody by virus brings about alterations in the structure of that virus by changing the conformation of its proteins (by allostery or distortion) or their association with each other or a third party. Unequivocal evidence to link this with neutralization is currently unavailable but it seems likely (to this reviewer) that at least some instances of neutralization involve antibody-induced changes in conformation. Lack of data is partly a technical problem since antibody itself is also a large and complex protein. Early data on non-viral systems are reviewed by Celada and Strom (1972) and Celada et al. (1983); they show that antibody releases heme from myoglobin (Crumpton 1966); and that antibody against the relevant native protein enhances activity of defective β-D-galactosidase (Rotman and Celada 1968; Acolla et al. 1983; Duncan 1983), catalase (Fernstein et al. 1971) and I-amino oxidase (Zimmerman et al. 1971), presumably by stabilizing and/or altering conformation. Also, the equilibrium between monomers and dimers of the E. coli alkaline phosphatase is shifted towards the dimer by reaction with anti-dimer antibodies (Lazdunskl et al. 1975). The activity of mutant and wild-type enzyme is also enhanced by specific antibodies, and most spectacularly by a Fab fragment (Pages et al. 1976). The NA activity of the HN protein of PIV-1 is enhanced by neutralizing antibody to site A (Yewdell and Gerhard 1982). Recently, antibodies have been shown to exert enzymic activities themselves through specificity for one of the metastable states of the appropriate antigen (Lerner and Tramontano 1987; Iverson and Lerner 1989; Tramontano and Schloeder 1989; Pollack et al. 1989).
KeywordsDepression Iodine Influenza Polypeptide Macromolecule
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