Subfamily: Chordopoxvirinae

Genus: Mustelpoxvirus


Distinguishing features

The Mustelpoxvirus genus includes a single species, Sea otterpox virus, members of which have been detected in sea otters from both California and Alaska, USA. Disease associated with sea otterpox virus infection is characterised by small superficially ulcerated skin lesions that are self-limiting. Most cases of disease are seen in young animals undergoing rehabilitation in sea-life rescue centres. There is no evidence to believe disease is significant in the wild. The potential for mustelpoxvirus being zoonotic is unknown.


Virions are brick-shaped with typical dumbbell electron dense cores. The size has not been reported and nothing is known about the ether-sensitivity of infection.

Genome organization and replication

The dsDNA genome of sea otterpox virus (128 kbp) encodes 132 genes, the smallest genome of a member of the subfamily Chrodopoxvirinae to have been sequenced; G + C content is approximately 31%. The majority of genes in the conserved core region of the virus are colinear with those of orthopoxviruses and most other viruses in the subfamily Chordopoxvirinae, although some unique genes, are also found in this region. The apparent closest relative to the mustelpoxviruses are the pteropopoxviruses, forming a separate clade in phylogenetic analyses of seven conserved genes (Jacob et al., 2018). The sea otterpox virus is considered to have eight genes unique within the poxviruses, including a potentially unique interleukin-18 binding protein.

For replication please see discussion under family description.

Species demarcation criteria

Currently a single species genus and therefore criteria have not been defined.