The genus Yatapoxvirus includes two species, Tanapox virus that includes tanapox virus (TANV), and Yaba monkey tumor virus that includes Yaba monkey tumor virus (YMTV). A third virus, Yaba-like disease virus (YLDV) is a member of the species Tanapox virus. Infection of primates with YMTV causes histiocytomas, subcutaneous tumour-like masses of mononuclear cells, most commonly located on the head and limbs. Viruses have been isolated from captive monkeys, baboons and experimentally-infected rabbits. Accidental human infection in the laboratory has been reported. Human infection due to TANV has been observed in equatorial Africa and in laboratory personnel handling infected primates. In primates, TANV produces localized cutaneous lesions that are thought to result from mechanical transmission by insects, this generally occurring during the rainy season in African rain forests.
Virions are brick-shaped with a dumbbell-shaped core, measuring approximately 300×250×200 nm.
Genome organization and replication
The genomic dsDNA ranges from approximately 135 kbp (YMTV) to approximately 145 kbp (TANV); the G+C content is 27% for TANV and 30% for YMTV. The virus genome is predicted to encode 139 (YMTV) or 155 (TANV) genes. The 10 kbp genome difference between YMTV and TANV results from the absence of a number of open reading frames, particularly at the left-hand end of the YMTV genome, with the remainder deleted at the right-hand end (Brunetti et al., 2003, Nazarian et al., 2007). The central core of the genome is conserved between the two viruses and is also conserved and co-linear with the majority of the mammalian chordopoxviruses. Phylogenetic analyses place the yatapoxviruses firmly within a clade including members of the genera Capripoxvirus, Suipoxvirus, Leporipoxvirus and Cervidpoxvirus.
For replication, please see discussion under family description.
Species demarcation criteria
The general chordopoxvirus criteria of <98% nucleotide identity across the central core of the genome is used to delineate species, whereas >98% identity indicates separate strains of the same species. Species demarcation criteria also consider RFLP analysis, genomic DNA sequencing studies, serological criteria including cross-protection in animals and plaque neutralization tests, geographical distribution, ecological niche and nature of the disease.