Hurt AC, Vijaykrishna D, Butler J, Baas C, Maurer-Stroh S, Silva-de-la-Fuente MC, Medina-Vogel G, Olsen B, Kelso A, Barr IG, González-Acuña D. 2014. Detection of evolutionarily distinct avian influenza A viruses in Antarctica. mBio 5(3):e01098-14. doi:10.1128/mBio.01098-14
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.
The fieldwork was funded by the Instituto Antártico Chileno as part of the project INACH T-27-10: “The common seabird tick Ixodes uriae (White,1852) as vector of pathogenic virus, bacteria and protozoa to penguins of the Antarctic environment.” The Melbourne WHO Collaborating Centre for Reference and Research on Influenza is supported by the Australian Government Department of Health. D.V. is funded by the Agency of Science,Technology and Research, Singapore, and the Ministry of Health, Singapore, and Singapore Ministry of Education Academic Research Fund grant MOE2011-T2-2-049.
We thank the staff of the Chilean Antarctic bases Bernardo O’Higgins and Arctowski for their help and assistance during our field work and acknowledge Marco Villarroel for producing the map in Fig. 1 and Ross
Lunt, CSIRO AAHL, Australia, for advice on the NP antibody ELISA.