Poxviridae. Poxviridae

Description of Poxviridae adapted from ICTVdb Virion Properties Morphology Virions consist of an envelope, a surface membrane, a core, and lateral bodies, or a surface membrane, a core, and lateral bodies. During their life cycle, virions produce extracellular particles and produce intracellular particles; can occur in two phenotypes; may be enveloped during their extracellular phase. The infection is initiated by extracellular virions. Virus may be sequestered within inclusion bodies that are not occluded and typically contain one nucleocapsid. Virus capsid is enveloped. Virions are generally ovoid and brick-shaped, or pleomorphic measuring 140-260 nm in diameter, or 160-190 nm in diameter (ovoid, 220-450 nm in length, or 250-300 nm in length (ovoid, 140-260 nm in height. Composed of an external coat containing lipid and tubular or globular protein structures enclosing one or two lateral bodies and a core, which contains the genome, dDisplaying tubular units, or globular units, or regular spiral filaments. The core is unilaterally concave, or is biconcave, or is cylindrical with one lateral body, or two lateral bodies. Lateral bodies are usually lens-shaped. Nested between the core membrane, or between the surface membrane. Physicochemical and Physical Properties Virions have a buoyant density in CsCl of 1.23-1.27 g cm-3. Nucleic Acid The genome is not segmented and contains a single molecule of linear double-stranded DNA. The complete genome is 130000-375000 nucleotides long. The genome has a guanine + cytosine content of 35-64 %, or 20 % (for Entomopoxviruses). The genome has terminally redundant sequences. The terminally redundant sequences have reiterated inverted terminal sequences which are tandemly repeated. The genome sequence is repeated at both ends. Double-stranded DNA is covalently. Double-stranded DNA is cross-linked at both ends. Proteins The viral genome encodes structural proteins and non-structural proteins. Lipids Lipids are present and located in the envelope. Virions are composed of 4% lipids by weight. The composition of viral lipids and host cell membranes are similar. The lipids are host derived and synthesized de novo (during the early phase of virus replication) and are derived from plasma membranes. Viral membranes include glycolipids.