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Commentary
Fujian H5 Sub-Clade In US Canada and Taiwan Match
Recombinomics Commentary
February 17, 2015 23:15
The above comments from the OIE report on H5N1 identified in a backyard farm in Chilliwack, British Columbia suggest that the sequences are closely related to the H5N1 in the United States, A/American_green-winged_teal/Washington/195750/2014. The full teal sequence was recently released and the H5 is the same sub-clade as the earlier H5N2 sequence from British Columbia, A/turkey/BC/FAV10/2014. Moreover, the USDA also released full sets of H5N2 sequences, A/Northern_pintail/Washington/40964/2014, which is closely related to the BC H5N2 sequence. Similarly, the H5 in the H5N8 sequence, A/gyrfalcon/Washington/41088-6/2014, is also from the same sub-clade, which was seen in the crane from Japan, A/crane/Kagoshima/KU1/2014. This sub-clade was also seen in the sequences from the outbreak in Taiwan, which included H5N2 A/Goose/Taiwan/0104/2015, H5N3 A/Goose/Taiwan/01042/2015, and H5N8 A/Goose/Taiwan/0103/2015.
Thus, all four serotypes reported in outbreaks in Taiwan and North America originated from the same parental H5N8, which arrived in North America and the reassorted with North American wild birds to produce H5N1 and H5N2. The H5N2 sequence has three wild bird gene segments (PB1, NP, and N2) while the H5N3 sequence has four wild bird segments (PB1, PA. N1, and NS).The H5N2 in Canada and the United States represents clonal expansion, and the description above suggests the H5N1 sequences in Canada and the United States also represents clonal expansion.
However, the reassortment events generating these two serotypes were independent, which is also true for the three serotypes in Taiwan, which have wild bird sequences from Asia in all three serotypes, including H5N8 where two of the gene segments (PB1 and NP) are from wild birds and distinct from the sequences found in the H5N8 in the crane in Japan or the teal in Washington, which have lineages that trace back to the early 2014 sequences from South Korea.
Thus, all of the novel sequences in Taiwan and North America are Fujian clade 2.3.4.4, but they are derived from the sub-clade represent by the crane, which are distinct from the sequences circulating in Europe, which originated from sequences found in Russia, A/wigeon/Sakha/1/2014.
The sequences in Russia and Europe have S227R, while the Taiwan and North American sequences all have S227, which may increase affinity for avian gal 2,3 receptors, facilitating transmission in birds.
In Taiwan the number of infected farms has surpassed 800, signaling efficient transmission in birds.In North American, transmission has been more limited, but the upcoming migration in the spring may lead to significantly more infections in farms in Canada and the United States.
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