Taiwan Fujian H5N2 H5N3 H5N8 Match British Columbia H5

Thursday, February 5, 2015
By Paul Martin

February 2, 2015

Council of Agriculture Animal and Plant Health Inspection and Quarantine Bureau has released a full set of protein sequences for H5N2 (A/GS/YL/0104/2015) and H5N3 (A/GS/KS/01042/2015) as well as nearly complete (all except PA) sequences for H5N8(A/GS/CY/0103/2015) at their website. Also including were BLAST results at GenBank for the nucleotide sequences for H5N2 as well as N8 and N3. The agency is to be commended for the prompt release of these important sequences.

These data showed that all three H5 sequences were closely related to the sub-clade represented by A/crane/Kagoshima/KU1/2014 from Japan and A/turkey/BC/FAV10/2014 in Canada. This sub-clade is distinct from the sub-clade circulating in Europe, while evolved from the sequences from the wigeon in Siberia, A/wigeon/Sakha/1/2014. Although both sub-clades evolved fro the clade sequences identified in Korea in early 2014, the Kagoshima sub-clade evolved independently and has distinguishing markers in each gene segment. In H5 one of the markers is 227S, which is common in bird isolates, but almost all H5 sequences from Korea have S227R. The exception is A/Baikal teal/Korea/H96/2014, which also has 227S, as does all three H5 serotypes from Taiwan.

The first US H5N2 sequence, A/Northern pintail/Washington/40964/2014, was said to be closest to A/bean goose/Korea/H40/2014, which has S227R, suggesting that at least two different H5N2 sub-clades are circulating in North America.

The recent sequences from Taiwan signal significant diversity. The H5N2 BLAST data indicates 5 of the 8 gene segments (PB2, PB1, PA, NP, N2) match wild bird sequences that are distinct from the sequences in South Korea. However, the NS sequence released also matches wild birds, indicating the H5N2 sequences in Taiwan form at least two different constellations with Korea / Wild Bird ratios of 2/6 and 3/5. Moreover, the 7 released gene sequences from H5N8 also have two wild bird segments (PB1 and NP), signaling more diversity than seen in the sub-clade in Europe, where all 8 gene segments match South Korean lineages.

In Taiwan, H5 has been confirmed on 655 farms, and the three serotypes continue to spread. However, a sub-set of farms have at least two H5 serotypes signaling co-circulation which could generate additional constellations through reassortment.

Similar diversity may exist in North America, but only 1 set of sequences has been released.Sequences from the 14 wild birds, 2 captive birds, and 6 farms should be released immediately.

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