The mechanism by which a pathogen, such as a virus, is transmitted from one host to another host.

Of the nature of, caused by, or relating to a virus or viruses.

Tool based on a virus which is used to deliver genetic material into a living organism (in vivo) or in cell culture (in vitro). (Source: Wikipedia)

The complete, infective form of a virus outside a host cell, with a core containing its genome and usually a capsid.