mBio S1 Supplemental – Global Flyways
# 8581
Published yesterday in the open access journal mBio, we have research that found an evolutionarily distinct avian flu virus (H11N2) among a small number samples (n=8) collected from just over 300 Adélie penguins inhabiting isolated Admiralty Bay and Rada Covadonga on the Antarctica Peninsula.
Although distinct from other flu viruses seen around the globe, two of its gene segments share common ancestry with South American AIVs, while the six remaining genes shared ancestry with either North American avian or equine viruses (H3N2).
Although other H11 viruses have been shown in the past to have at least some ability to infect humans (see A Little Background On H11 Avian Influenzas) this virus is described at primarily adapted to avian receptor cells. The virus failed to replicate efficiently in inoculated ferrets, suggesting this virus has had little interaction with mammalian species.
Molecular clock analysis suggests that this virus has been cut off from other flu viruses - evolving on its own - for between 49 and 80 years.
I’ve only excerpted some highlights. There is a lot more in the study, so follow the link to read:
Detection of Evolutionarily Distinct Avian Influenza A Viruses in Antarctica
Aeron C. Hurta,b, Dhanasekaran Vijaykrishnac, Jeffrey Butlera, Chantal Baasa,b, Sebastian Maurer-Strohd,e,f, M. Carolina Silva-de-la-Fuenteg, Gonzalo Medina-Vogelh, Bjorn Olseni, Anne Kelsoa, Ian G. Barra,b, Daniel González-Acuñag
ABSTRACT
Distinct lineages of avian influenza viruses (AIVs) are harbored by spatially segregated birds, yet significant surveillance gaps exist around the globe. Virtually nothing is known from the Antarctic. Using virus culture, molecular analysis, full genome sequencing, and serology of samples from Adélie penguins in Antarctica, we confirmed infection by H11N2 subtype AIVs.
Their genetic segments were distinct from all known contemporary influenza viruses, including South American AIVs, suggesting spatial separation from other lineages. Only in the matrix and polymerase acidic gene phylogenies did the Antarctic sequences form a sister relationship to South American AIVs, whereas distant phylogenetic relationships were evident in all other gene segments. Interestingly, their neuraminidase genes formed a distant relationship to all avian and human influenza lineages, and the polymerase basic 1 and polymerase acidic formed a sister relationship to the equine H3N8 influenza virus lineage that emerged during 1963 and whose avian origins were previously unknown. We also estimated that each gene segment had diverged for 49 to 80 years from its most closely related sequences, highlighting a significant gap in our AIV knowledge in the region.
We also show that the receptor binding properties of the H11N2 viruses are predominantly avian and that they were unable to replicate efficiently in experimentally inoculated ferrets, suggesting their continuous evolution in avian hosts. These findings add substantially to our understanding of both the ecology and the intra- and intercontinental movement of Antarctic AIVs and highlight the potential risk of an incursion of highly pathogenic AIVs into this fragile environment.
IMPORTANCE Avian influenza viruses (AIVs) are typically maintained and spread by migratory birds, resulting in the existence of distinctly different viruses around the world. However, AIVs have not previously been detected in Antarctica.
In this study, we characterized H11N2 viruses sampled from Adélie penguins from two geographically different sites in Antarctica and show that the segmented AIV genome diverged between 49 and 80 years ago from other AIVs, with several genes showing similarity and shared ancestry with H3N8 equine influenza viruses. This study provides the first insight into the ecology of AIVs in Antarctica and highlights the potential risk of an introduction of highly pathogenic AIVs into the continent.
