What does the molecular structure of viruses tell us about viral functions?

The structures of the protein shell of a number of simple icosahedral RNA plant and animal viruses are now known at atomic resolution. In addition, components of viral capsids such as the haemagglutinin and neuraminidase spikes of influenza virus and the hexon unit of adenovirus are known in similar detail. These structures have provided a wealth of information on viral assembly, viral disassembly, the antigenic surface on viruses available to neutralizing antibodies, the host cell receptor attachment site, fusion of viral particles with the host cell, processing of polyproteins during maturation and the manner in which antiviral agents can interfere with the function of a viral capsid.