Papillomavirus in healthy skin of Australian animals
Antonsson, A & McMillan, NAJ 2006, Journal of General Virology, vol. 87, no. 1, pp. 3195-3200.
Papillomaviruses have been detected in one monotreme and two marsupial species in Australia, including the koala. From samples taken from several captive animal environments across Queensland including Lone Pine Koala Sanctuary, three putative and potential new papillomavirus types in koalas were identified. Of those koalas sampled, 14% tested positive for papillomavirus DNA attributable to one of these three papillomavirus types. The putative new koala papillomavirus type KoAA1 is genetically distinct from all previously described human and animal papillomaviruses.
Papillomaviruses are a group of DNA viruses that are commonly found in the healthy skin of vertebrates. While many papillomavirus types are asymptomatic, others can result in lesions where they replicate in bodily surface tissues. This investigation of the presence and types of papillomaviruses in Australian fauna is novel as papillomaviruses in this group of animals have not previously been described despite the ubiquity of the viruses. While the overall prevalence of papillomaviruses in the Australian species sampled in this study was only 5%, a previous study including a greater range of species from around the world reported papillomavirus presence to be 36%. Rather than papillomavirus presence being much lower in Australian species than internationally, it is possible that the papillomavirus types affecting Australian fauna are genetically isolated from international types and are therefore underreported due to poor detectability using existing primers.
Australia is home to several unique and primitive species of the monotreme and marsupial taxonomic groups. Their uniqueness is attributable to their independent evolution since the separation of the Australian landmass from the other continents. The findings of this study prove that these primitive animals, including echidnas, koalas and Eastern Grey kangaroos, are included in the broad range of species infected by papillomaviruses. The distinct evolutionary trajectories of these primitive species explain the fact that the new putative koala papillomavirus type KoAA1 appeared as a new branch, and possibly as a new genus, in the phylogenetic tree.
These findings are significant because they are not only the first to describe papillomavirus sequences infecting koalas, but more broadly emphasise how commonly papillomaviruses infect the healthy skins of Australian vertebrates. The identification of five new animal papillomavirus types demonstrates that we are far from completing the papillomavirus phylogenetic tree, with new genera continuing to be discovered.
Summarised by Joanna Horsfall
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