Biophysical Studies of the Interactions Between Small Molecule Inhibitors and Viral Protein Targets

Being a cause of over 4 million cases of severe illness and 300,000 deaths per year, Influenza virus is arguably one of the world largest health threats. This virus enters cells in an endosome dependent manner through the action of hemagglutinin (HA), the major regulator of viral entry process. During the endosome evolution HA undergoes a series of pH induced conformational changes that lead to the fusion of viral and endosomal membranes and the release of viral material into the cell. The central role of HA for influenza infectivity makes it a very attractive drug target. Large number of antibodies, peptides and small molecule inhibitors that block HA function has been developed over the years. However, none of the current treatment options against influenza virus infection target hemagglutinin. In this research we have chosen several small molecule inhibitors of HA-induced fusion and characterized their modes of action using a combination of structural biology and virology methods. A combination of nuclear magnetic resonance (NMR), X-ray crystallography, mutagenesis and several other approaches was applied to gain insight into the binding sites of these compounds and their inhibition mechanisms. After the detailed characterization, all obtained information was then used to navigate the chemical optimization of the select group of inhibitors.