H9N2 Bird Flu in Swine in Korea in 2005
Recombinomics Commentary
April 30, 2005
>> However, it is important to continue scientific studies to verify the presence of an H9 virus in S. Korea considering that there have been reports describing the presence of H9N2 viruses in other countries in Asia. <<
The above comment from a draft of a WHO statement on its investigation of WSN/33 in Korean swine acknowledges the agency's continued interest in H9N2 in swine in Korea. A recent published report described H9N2 in various birds in live markets in Korea in 2003. H3N2 and H6N1 were also isolated from the live markets. Moreover, one of the swine sequences from 2004 did have 8 avian genes. However, this isolate, S452, had genes that were very similar to the 2003 avian isolates.
In contrast, the avian genes in the six swine isolates with WSN/33 sequences were distinct from the 2003 isolates, although those Korean isolates were the closest match. Thus, the swine 2004 H9N2 isolates appear to involve a new version of Korean H9N2 viruses. This analysis has focused more on HA and NA because there were no avian PB1, PA, or NP genes in the swine isolates.
New data from the swine fatally infected with WSN/33 in 2005 also have H9N2 sequences. These 2005 H9N2 isolates are slightly different than the 2004 isolates and are also readily distinguished from the 2003 H9N2 sequences.
Thus, like the 2005 WSN/33 sequences. H9N2 is also evolving and the sequence data suggests that the WSN/33 infections are recent and probably happened in 2004.
They are still evolving and spreading in 2005.
The genetic instability, death of pigs, and lack of WHO investigations of the WSN/33 sequences in pigs in South Korea are cause for concern.
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