W0304

Structural Biology of Viral Entry. Stephen C. Harrison, Molecular and Cellular Biology, HHMI/Harvard Univ., Cambridge MA 02138

Enveloped viruses enter cells by membrane fusion; non-enveloped viruses must transiently disrupt a membrane, in order to get their genomes into the cytoplasm or nucleus. The structures of fusion proteins from viral envelopes show at least two distinct molecular designs that can accomplish this process. The structures of non-enveloped viral entry proteins are just now yielding insights into the molecular mechanism of penetration. Structures to be discussed include fusion proteins from HIV-1 and from tick-borne encephalitis virus, and entry machinery from polyoma viruses, rotaviruses and reoviruses.