Basis for fusion inhibition by peptides: analysis of the heptad repeat regions of the fusion proteins from Nipah and Hendra viruses, newly emergent zoonotic paramyxoviruses.

Nipah virus (NiV) and Hendra virus (HeV) are novel zoonotic members of the Paramyxoviridae family and are the prototypes for a newly designated genus, Genus Henipavirus. Recent studies have shown that paramyxovirus might adopt a similar mechanism of virus fusion-entry. Under this mechanism, the two highly conserved heptad repeat (HR) regions, HR1 and HR2, in the fusion (F) protein, seem to show characteristic structure in the fusion core: the formation of a 6-helix coiled-coil bundle. The three HR1s form the alpha-helix coiled-coil surrounded by three HR2s. In this study, the two HR regions of NiV or HeV were expressed in an Escherichia coli system as a single chain and the results do show that HR1 and HR2 interact with each other in both NiV and HeV and form typical 6-helix coiled-coil bundles. This provides the molecular basis of HR2 inhibition to NiV and HeV fusion as observed in an earlier report.