Abstract
BackgroundOver the past 20 years, many marine seabird populations have been gradually declining and the factors driving this ongoing deterioration are not always well understood. Avipoxvirus infections have been found in a wide range of bird species worldwide, however, very little is known about the disease ecology of avian poxviruses in seabirds. Here we present two novel avipoxviruses from pacific shearwaters (Ardenna spp), one from a Flesh-footed Shearwater (A. carneipes) (SWPV-1) and the other from a Wedge-tailed Shearwater (A. pacificus) (SWPV-2).ResultsEpidermal pox lesions, liver, and blood samples were examined from A. carneipes and A. pacificus of breeding colonies in eastern Australia. After histopathological confirmation of the disease, PCR screening was conducted for avipoxvirus, circovirus, reticuloendotheliosis virus, and fungal agents. Two samples that were PCR positive for poxvirus were further assessed by next generation sequencing, which yielded complete Shearwaterpox virus (SWPV) genomes from A. pacificus and A. carneipes, both showing the highest degree of similarity with Canarypox virus (98% and 67%, respectively). The novel SWPV-1 complete genome from A. carneipes is missing 43 genes compared to CNPV and contains 4 predicted genes which are not found in any other poxvirus, whilst, SWPV-2 complete genome was deemed to be missing 18 genes compared to CNPV and a further 15 genes significantly fragmented as to probably cause them to be non-functional.ConclusionThese are the first avipoxvirus complete genome sequences that infect marine seabirds. In the comparison of SWPV-1 and −2 to existing avipoxvirus sequences, our results indicate that the SWPV complete genome from A. carneipes (SWPV-1) described here is not closely related to any other avipoxvirus genome isolated from avian or other natural host species, and that it likely should be considered a separate species.
Highlights
Over the past 20 years, many marine seabird populations have been gradually declining and the factors driving this ongoing deterioration are not always well understood
The genetic distance and novel genome structure of Shearwaterpox virus 1 (SWPV-1) from A. carneipes considered to be missing 43 genes likened to Canarypox virus (CNPV) and contained 4 predicted genes which are not found in any other poxvirus and is overall sufficiently genetically different to be considered a separate virus species
The Shearwaterpox virus 2 (SWPV-2) complete genome was missing 18 genes compared to CNPV, with a further 15 genes significantly fragmented as to probably cause them to be nonfunctional
Summary
Over the past 20 years, many marine seabird populations have been gradually declining and the factors driving this ongoing deterioration are not always well understood. Avipoxvirus infections have been found in a wide range of bird species worldwide, very little is known about the disease ecology of avian poxviruses in seabirds. Sarker et al BMC Genomics (2017) 18:298 only six avipoxvirus genomes have been published; a pathogenic American strain of Fowlpox virus (FPVUS) [7], an attenuated European strain of Fowlpox virus (FP9) [8], a virulent Canarypox virus (CNPV) [9], a pathogenic South African strain of Pigeonpox virus (FeP2), a Penguinpox virus (PEPV) [3], and a pathogenic Hungarian strain of Turkeypox virus (TKPV) [10] These genome sequences demonstrate that avipoxviruses have diverged considerably from the other chordopoxviruses (ChPVs), approximately 80 genes have been found to be conserved amongst all ChPVs and to comprise the minimum essential poxvirus genome [11]. With the exception of TKPV (188 kb), avipoxvirus genomes (266–360 kb) tend to be bigger than those of other ChPVs due in part to multiple families of genes
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