The mechanism of penetration of non-enveloped viruses remains poorly understood, although they are relatively small and simple in structure 18. Fusion of the more complex enveloped viruses is ...

The measles virus is an enveloped virus bearing a lipid bilayer. The bilayer holds the receptor binding hemagglutinin (H) protein and the fusion (F) protein. For infection to happen, the H protein ...

That means H5N1 is identified as having H subtype 5 and N subtype 1. Influenza is an enveloped virus, meaning that it takes its outer layer from the host cell that it's infecting, enveloping itself.