Family: Poxviridae

Subfamily: Chordopoxvirinae


Distinguishing features

The subfamily includes brick-shaped or ovoid poxviruses of vertebrates with a linear dsDNA genome of 128–360 kbp with a G+C content ranging from approximately 25 % (Yokapoxvirus) to 67% (Scuiripoxvirus). This is in contrast to a G+C content of approximately 20% found in members of the Entomopoxvirinae. Extensive serologic cross-reaction and cross-protection is observed between members of a genus, though this is less obvious among the avipoxviruses. A common, conserved co-linear signature core of genes within genera (and in the case of mammalian viruses, spanning genera) is generally maintained with most divergence amongst members occurring at the terminal extremities of the genome. The co-linear signature of core genes appears different for mammalian, avian, and piscine genera, which are all again different from members of the subfamily Entomopoxvirinae. Disease caused by members of the subfamily Chordopoxvirinae is characterized by localized cutaneous lesions, skin nodules or disseminated rash. Incubation periods can be anywhere from 1–3 weeks with progression through to resolution in approximately 4–6 weeks. Prior infection generally provides robust immunity to further infection, with the noticeable exception of viruses in the species Molluscum contagiosum virus and in the genus Parapoxvirus. Infection may be relatively inapparent in the natural host, but can be significant in susceptible hosts (McFadden 2005). Mortality rates can be high (e.g. members of the species Variola virus, these being the causative agent of smallpox) and/or economically significant (e.g. capripoxviruses).

Genus demarcation criteria

  • · Natural host range. In some cases host range may be very narrow, and in others very broad, but in most cases the delineation of the natural host(s) is a defining characteristic. Exceptions include genera where members are zoonotic, and viruses of ruminants which can come from at least three different genera.

  • · Gene content comparisons. The variability in the content and conservation of gene sequences between poxvirus isolates can serve as a distinguishing characteristic.

  • · Organization of the genome. Syntenic relationships between genes may in some cases serve to distinguish taxa. However, conservation of gene synteny, particularly in the central core, can frequently be so high that the resolving power is not available to distinguish between taxa.

  • · Phylogenetic analysis. Taxonomic groupings can in most cases be readily inferred from the evolutionary clades observed following phylogenetic inference.

Related, unclassified viruses

Virus name

Accession number


Berlin squirrelpox virus



carp edema virus



cetacean poxvirus 1



cheloniid poxvirus 1






teiidae poxvirus 1



Virus names and virus abbreviations are not official ICTV designations.