Protease-dependent virus tropism and pathogenicity

Viral tissue tropism in a susceptible host is often determined by virus-receptor interactions. Nevertheless, closely related viruses utilizing the same receptor molecules can display striking differences in tropism, or a virus can cause a localized infection despite the widespread occurrence of the receptor. These events are now explained by another mechanism of tropism, in which host proteases play a major role by activating viral fusion glycoproteins.