Viral infectious diseases
A viral disease (or viral infection, or infectious disease) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells Double-stranded DNA families: three are non-enveloped (Adenoviridae, and Polyomaviridae) and two are enveloped (Herpesviridae and Poxviridae). All of the non-enveloped families have icosahedral capsids. Partly double-stranded DNA viruses: Hepadnaviridae. These viruses are enveloped.