Mechanisms of Viral Entry and Replication |
Influenza virus binds via its envelope protein hemagglutinin (HA) sialic acid (SA) residues of glycoproteins on the plasma membrane of the host cell. The affinity of a single HA-SA pair is low (103 M-1) compared to the overall affinity between virus and cell surface caused by multiple simultaneous interactions. For example, the affinity between virus and erythrocytes - serving as a model for a host cell - is about 1013 M-1. Multivalency is ubiquitous in biology and can dramatically enhance affinities. We use synthetic polymers with multiple sialic acid moieties to investigate their inhibitory effect on virus binding and fusion. The aim of this study is to gain insights into the molecular mechanism and the effect principles of multivalent inhibitors. Furthermore we aim to measure the accurate affinity between a virus particle and the target erythrocyte membrane by using a new developed optical tweezers system. With this approach we are able to explore the action of multivalent inhibitors on the single molecule level. Furthermore, we study binding of labelled virus particles to human erythrocytes using fluorescence activated cell sorting (FACS). The fusion activity is examined by detection of fluorescence de-quenching of R 18 labeled viruses attached to human erythrocyte ghosts.
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