|
" The hemagglutinin gene was placed into a clade within the H5 American LPAIV lineage, clustering with AIVs isolated from ducks in the United States during 2007–2014 and blue-winged teals from Guatemala in 2010"
Avian Influenza Virus H5 Strain with North American and Eurasian Lineage Genes in an Antarctic Penguin
Previous studies have reported avian influenza virus (AIV)–positive serum samples obtained from Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarcticus), and gentoo (Pygoscelis papua) penguins (1–4). Only recently was an H11N2 subtype virus isolated from Adélie penguins in Antarctica (5). We performed AIV surveillance in the Antarctic Peninsula to identify the strains currently circulating in different penguins species in this area.
During 2015–2016, we sampled penguin colonies from 9 locations on the Antarctic Peninsula. We collected 138 blood samples from Adélie penguins at Ardley Island (62°13′S, 58°56′W), Arctowski Base (62°9′S, 58°28′W), and Bernardo O’Higgins Base (63°19′S, 57°53′W) and identified 5 serum samples positive for influenza. We also collected 513 cloacal swabs from Adélie, chinstrap (Technical Appendix Figure 1, panel A), and gentoo penguins from Mikkelsen Harbor (63°54′S, 60°47′W), Dorian Bay and Port Lockroy (64°48′S, 63°30′W), Pleneau Island (65°06′S, 64°04′W), Brown Base (64°53′S, 62°52′W), Orne Harbor (64°37′S, 62°32′W), and Aitcho Island (62°23′S, 59°46′W) during January–March of 2 consecutive seasons (2015 and 2016; Technical Appendix Figure 1, panel B). Quantitative reverse transcription PCR (RT-PCR) analysis of the matrix segment (6) identified 21 positive AIV samples from penguins (8 chinstrap, 13 gentoo) on Aitcho Island, demonstrating the presence of AIV in 2 additional penguin species in a new location in Antarctica.
Using multisegment RT-PCR performed with influenza-specific universal primers, we amplified all 8 virus segments from a chinstrap penguin specimen, which yielded cDNA products suitable for next-generation sequencing with a HiSeq 2500 System (Illumina, San Diego, CA, USA). This virus was subtyped as an H5N5 and named A/chinstrap_penguin/Antarctica/B04/2015 (H5N5). Analysis of its cleavage site confirmed this was a typical low pathogenicity AIV (LPAIV) containing cleavage motif PQRETRGLF (7).
To trace the origin of this H5N5 virus, we performed phylogenetic analyses of its hemagglutinin and neuraminidase genes (Figure, panels A, B; Technical Appendix Figures 2, 3). The hemagglutinin gene was placed into a clade within the H5 American LPAIV lineage, clustering with AIVs isolated from ducks in the United States during 2007–2014 and blue-winged teals from Guatemala in 2010 (Technical Appendix Figure 2). This finding suggests a possible introduction of this H5 AIV into Antarctica via the Pacific or the Mississippi–American flyways, although we cannot rule out that this H5 strain is endemic to other South America locations.
The timing of arrival of migratory birds that breed in Antarctica (e.g., skua, shags, petrel, and gulls) overlaps with that of the penguins as they return to colonies for breeding and nesting during the summer in the Southern Hemisphere. These birds share a habitat, enabling close contact (5,8) and introducing the possibility of AIV spillover from flying birds to penguins. The chinstrap penguin H5 strain also clustered near the H5 strain isolated in 2008 from a kelp gull (Larus dominicanus) in Chile (9), indicating a potential route of transmission and introduction of AIV into Antarctic penguins (Figure, panel A). Kelp gull colonies are found in the Antarctic, the sub-Antarctic territory, and along the coastline of Chile and Argentina. Hence, gulls and other intermediate vector hosts, such as the south polar skua (Stercorarius maccormicki), might represent natural reservoirs that play a role in the introduction and maintenance of AIVs into Antarctica.
|
"recent introduction of an H5N5 AIV, predominantly of North American-like origin"
Evidence for the Introduction, Reassortment, and Persistence of Diverse Influenza A Viruses in Antarctica
ABSTRACT
Avian influenza virus (AIV) surveillance in Antarctica during 2013 revealed the prevalence of evolutionarily distinct influenza viruses of the H11N2 subtype in Adélie penguins. Here we present results from the continued surveillance of AIV on the Antarctic Peninsula during 2014 and 2015. In addition to the continued detection of H11 subtype viruses in a snowy sheathbill during 2014, we isolated a novel H5N5 subtype virus from a chinstrap penguin during 2015. Gene sequencing and phylogenetic analysis revealed that the H11 virus detected in 2014 had a >99.1% nucleotide similarity to the H11N2 viruses isolated in 2013, suggesting the continued prevalence of this virus in Antarctica over multiple years. However, phylogenetic analysis of the H5N5 virus showed that the genome segments were recently introduced to the continent, except for the NP gene, which was similar to that in the endemic H11N2 viruses. Our analysis indicates geographically diverse origins for the H5N5 virus genes, with the majority of its genome segments derived from North American lineage viruses but the neuraminidase gene derived from a Eurasian lineage virus. In summary, we show the persistence of AIV lineages in Antarctica over multiple years, the recent introduction of gene segments from diverse regions, and reassortment between different AIV lineages in Antarctica, which together significantly increase our understanding of AIV ecology in this fragile and pristine environment.
IMPORTANCE Analysis of avian influenza viruses (AIVs) detected in Antarctica reveals both the relatively recent introduction of an H5N5 AIV, predominantly of North American-like origin, and the persistence of an evolutionarily divergent H11 AIV. These data demonstrate that the flow of viruses from North America may be more common than initially thought and that, once introduced, these AIVs have the potential to be maintained within Antarctica. The future introduction of AIVs from North America into the Antarctic Peninsula is of particular concern given that highly pathogenic H5Nx viruses have recently been circulating among wild birds in parts of Canada and the Unites States following the movement of these viruses from Eurasia via migratory birds. The introduction of a highly pathogenic influenza virus in penguin colonies within Antarctica might have devastating consequences.
|
|
|
|
"circumpolar birds are frequently infected by intercontinental reassortant viruses"
SUMMARY
Wild waterbirds, specifically waterfowl, gulls, and shorebirds, are recognized as the primordial reservoir of influenza A viruses (IAVs). However, the role of seabirds, an abundant, diverse, and globally distributed group of birds, in the perpetuation and transmission of IAVs is less clear. Here we summarize published and publicly available data for influenza viruses in seabirds, which for the purposes of this study are defined as birds that exhibit a largely or exclusively pelagic lifestyle and exclude waterfowl, gulls, and shorebirds, and we review this collective dataset to assess the role of seabirds in the influenza A ecology. Since 1961, more than 40,000 samples have been collected worldwide from the seabirds considered here and screened, using a variety of techniques, for evidence of active or past IAV infection. From these data, the overall prevalence of active infection has been estimated to be very low; however, serological data provide evidence that some seabird species are more frequently exposed to IAVs. Sequence data for viruses from seabirds are limited, except for murres (common murre, Uria aalge, and thick-billed murre, Uria lomvia; family Alcidae) for which there are full or partial genome sequences available for more than 80 viruses. Characterization of these viruses suggests that murres are infected with Group 1 hemagglutinin subtype viruses more frequently as compared to Group 2 and also indicates that these northern, circumpolar birds are frequently infected by intercontinental reassortant viruses. Greater temporal and spatial sampling and characterization of additional viruses are required to better understand the role of seabirds in global IAV dynamics.
|
First detection of avian influenza virus (H4N7) in Giant Petrel monitored by geolocators in the Antarctic region
Abstract
This study presents the results of the virologic analysis and year-round movements of a Southern Giant Petrel that tested positive for avian influenza virus. Data were collected in two areas of Antarctica, where 299 Southern Giant Petrel adults and chicks were sampled. One-step real-time RT-PCR detected the presence of the avian influenza A virus in only one individual of the total Southern Giant Petrel sampled. The H4N7 subtype detected was compared to other H4N7 virus sequences and results suggest that segments of E96/H4N7 were closely related to avian influenza viruses of Anseriformes and Charadriiformes from North America. The geolocator that reported the year-round movements of the infected Southern Giant Petrel was retrieved. It was observed that this infected individual visited areas close to the Antarctic Peninsula during summer/spring and migrated to northern areas near South America and the Falkland Islands during the non-breeding season. Our results point out the first evidence of avian influenza virus H4N7 in Giant Petrels. Furthermore, the genetic similarity of the sequenced virus provides evidence of viral connections between North America and the Antarctic Peninsula. The migratory routes of several species in which avian influenza virus has been detected are coincident with the non-breeding area frequented by this single Southern Giant Petrel. Thus, movements of Southern Giant Petrel should be monitored to enable the determination of potential points of contact with other coastal seabird species along with the assessment of the dispersal routes of viruses.
|
|
|
