<P> A viral protein is both a component and a product of a virus . Viral proteins are grouped according to their functions, and groups of viral proteins include structural proteins, nonstructural proteins, regulatory, and accessory proteins . Viruses are non-living and they do not have the means to reproduce on their own . They depend on their host cell's metabolism for energy, enzymes, and precursors, in order to reproduce . As such, viruses do not code for many of their own viral proteins, but rather, they use the host cell's machinery to produce the viral proteins they require for replication . </P> <P> Most viral structural proteins are components for the capsid and the envelope of the virus . </P>

What is needed for virus proteins to be made