Identification of a novel Adélie penguin circovirus at Cape Crozier (Ross Island, Antarctica)

Understanding the causes of disease in Antarctic wildlife is crucial as many of these species are already threatened by environmental changes brought about by climate change. In recent years, Antarctic penguins have been showing signs of an unknown pathology: a feather disorder characterised by missing feathers resulting in exposed skin. During the 2018-19 austral summer breeding season at Cape Crozier colony on Ross Island, Antarctica, for the first time we observed an Adlie penguin chick missing down over most of its body. A guano sample was collected from the nest of the featherless chick and, using high throughput sequencing we identified a novel circovirus. Using abutting primers, we amplified the full genome, which we cloned, and Sanger sequenced to determine the complete genome of the circovirus. The Adlie penguin guano-associated circovirus genome shares 99% pairwise identity to the one identified in 2018-19. This is the first report of a circovirus associated with a penguin species and could be a possible etiological agent of the feather-loss disorder in Antarctic penguins.