The Molluscipoxvirus genus includes a single virus species, Molluscum contagiosum virus, members of which exclusively infect humans, although similar pathological signs have been noted in horses, donkeys and chimpanzees, and are possibly caused by related viruses. Disease manifests as small, benign skin tumours in healthy individuals. The tumours are normally self-limiting, spontaneously regressing over a few months, but can become extensive in the immunocompromised. There is little inflammatory reaction within the skin surrounding the lesions and only a weak generalized immune response to infection. The localized lesions contain enlarged cells with cytoplasmic inclusions known as molluscum bodies. Transmission is thought to be mechanical, through broken skin coming into contact with fomites. Infections can recur and lesions may be disfiguring when combined with bacterial infections. The restricted host range noted in vivo is mirrored in vitro, with no universal method accepted for growing the virus in vitro.
Virions are brick-shaped, about 320×250×200 nm. Their buoyant density in CsCl is about 1.288 g cm−3.
Genome organization and replication
The genomic DNA is about 192 kbp, encoding approximately 174 genes: G + C content is 64%. The genes of the central core region of the genome are generally conserved and co-linear with those of orthopoxviruses, but those at either end of the genome show extensive divergence. Indeed, approximately 60 genes present in orthopoxviruses and thought to interact with the host immune response, are missing from molluscum contagiosum virus, but are replaced by a similar number that may be related to its biology.
For replication please see discussion under family description.
Species demarcation criteria
Currently, there is only a single species in the genus and therefore criteria have not been defined.
Related, unclassified viruses
equine molluscum contagiosum-like virus
Virus names and virus abbreviations are not official ICTV designations.