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Commentary
Fujian H5N8 Wild Bird Clonal Expansion In The
United States
Recombinomics Commentary
February 23, 2015 16:00
The USDA also released full sets of H5N8 sequences from a backyard farm in Douglas County, Oregon (A/guinea fowl/Oregon/41613-1/2014 and A/chicken/Oregon/41613-2/2014), which matched each other as well as the first confirmed H5N8 case (A/gyrfalcon/Washington/41088-6/2014), confirming that H5N8 is also expanding clonally in the United States. This expansion is also supported by the above H5N2 sequences, which have a 5/3 ratio between H5N8 sequences and North American wild birds, which contribute PB1, NP and N2 to the H5N2 constellation, or a 4/4 ratio between H5N8 and H5N1 sequences (A/American green-winged teal/Washington/195750/2014) where wild bird origins are found for PB1, PA, N1, NS.
Thus, the clonally expanding H5N8 is the parental sequence for the other two serotypes identified in North America, H5N1 and H5N2. However, the North American H5N8 is most closely related to the crane sequence from Japan, (A/crane/Kagoshima/KU1/2014). That sequence is also closely related to the sequences in Taiwan, where the number of H5 confirmed farms has increased to 841. In Taiwan the H5N8 has acquired two gene segments from wild birds in Asia (PB1 and PA), while H5N2 has 1 4/4 ratio, while H5N3 has only two gene segments from H5N8, N5 and MP (H5N2 A/Goose/Taiwan/0104/2015, H5N3 A/Goose/Taiwan/01042/2015, and H5N8 A/Goose/Taiwan/0103/2015).
Thus, in Taiwan and North America, and H5N8 parental clade has produced two additional serotypes via ressortment with local wild birds. In North America the three serotypes has clonally expanded as indicated by sequence data for H5N8 and H5N2, or an OIE description of H5N1 in Fraser Valley. The H5N8 has been widely reported in the United States (see H5N8 map), while H5N2 has been limited to Fraser valley and three northwestern states (Washington, Oregon, and Idaho – see H5N2 map), and H5N1 has been found in Washington and Fraser Valley – see H5N1 map).
However, the frequencies for each serotype may have expanded over the winter and impacts may be significantly higher in the spring as wild birds migrate back to Canada and Alaska.
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