Subfamily: Chordopoxvirinae

Genus: Crocodylidpoxvirus

Distinguishing features

The first virus to be classified in a species in the genus Crocodylidpoxvirus was isolated from a Nile crocodile in Zimbabwe, but similar poxviruses have been reported in crocodiles and caimans worldwide, particularly in South America, Australia and in various countries of southern Africa. Disease has not been reported from the wild, but instead is associated with crocodile farms, largely affecting hatchlings and younger animals. Skin lesions appear over all parts of the body, ranging from wart-like lesions to deeply penetrating epidermal cysts that lead to the downgrading of skins. Ulcers around the mouth, eyes and nostrils have also been reported. Morbidity is high and although mortality is generally low, in some outbreaks of disease mortality of up to 30% has been reported. There is no evidence that members of the genus Crocodylidpoxvirus are zoonotic.

Virion

Virions are brick-shaped and similar in size to those of orthopoxviruses, being 160 × 200 × 230 nm, but with rounded corners, and having a dumbbell-shaped core with two electron-dense lateral bodies. However, the surface morphology is more reminiscent of the parapoxviruses with a regular cross-hatched spiral coil. Nothing is known about the ether sensitivity of infection.

Genome organization and replication

The dsDNA genome is approximately 190 kbp, encoding approximately 173 genes; G + C content is 62%. The central part of the genome is largely co-linear with that of the orthopoxviruses, but also contains 14 genes of unknown function that disrupt this co-linearity (Afonso et al., 2006). The two terminal regions contain 48 genes of unknown function the majority of which have no recognisable counterparts in the other poxvirus genera. These are presumed, as with the other poxviruses, to encode proteins that act as immunomodulators and/or dictate host range, but since little is known about the reptile immune system this has yet to be confirmed. In pairwise comparisons crocodilepox virus proteins have greatest homology to those of molluscum contagiosum virus.

For replication please see discussion under family description.

Species demarcation criteria

There is only one species in the genus, so demarcation criteria have not been defined.

Related, unclassified viruses

Virus names and virus abbreviations are not official ICTV designations.