Commentary
H5N1 Uvs Lake Migration to Japan
Recombinomics Commentary 14:35
May 6, 2008
The results showed that the K11 strain had above 99 percent homology with the other three strains for all gene segments, suggesting that all four strains are closely related. In addition, homology with two strains from last year's outbreak of highly pathogenic avian influenza in South Korea was also above 99 percent, and homology with the A/whooper swan/Mongolia/2/2006 virus isolated from whooper swans in Mongolia was also above 99 percent for all segments, indicating that these viruses are closely related.
Analysis of the HA gene of the H5N1 highly pathogenic avian influenza virus isolated from the mountain hawk-eagle found the virus to have the G-E-R-R-R-K-K-R amino acid sequence in the HA cleavage region typical of virulent types. As for homology with other H5 viruses, it is most homologous (at least 99.7 percent) with the virus isolated from wild birds in Mongolia in 2006. A phylogenetic tree for the HA gene was created in order to analyze the details of relationships with other viruses (see attached figure). It is closest to the A/chicken/Miyazaki/K11/07 strain isolated in Miyazaki, demonstrating that this virus is also a Qinghai Lake-type.
The above comments from a report on the 2007 outbreak of H5N1 in Japan (see isolates below) confirm that the H5N1 was closely related to the H5N1 from South Korea in late 2006, which was related the Uvs Lake outbreak in Mongolia and Siberia in the summer of 2006. The pattern in 2006 / 2007 was similar to 2003 / 2004. H5N1 in South Korea at the end of the calendar year was subsequently found in Japan a month or two later.
This year that pattern has probably repeated, although the outbreak in South Korea began as wild birds began migrating to the north, and the dead and dying wild birds in Japan were discovered under enhanced surveillance. It is likely that the H5N1 in both countries represents the latest version of the Uvs Lake strain in the region.
However, this year the H5N1 in South Korea is a record levels, and the location of the H5N1 positive swans in Japan are in Akita and Hokkaido (see satellite map), which are where there has not been previously reported outbreaks. These northern locations suggest H5N1 will migrate into northeastern Siberia, which may lead to migration into North America.
The record levels of H5N1 in South Korea follows record outbreaks in India and Bangladesh, which may signal a higher endemic level and further geographic spread of H5N1 via migrating birds.
A/Ck/Miyazaki/S749/07
A/Ck/Miyazaki/H358/07
A/Ck/Miyazaki/K11/07
A/Mountain hawk-eagle/Kumamito/1/07
A/Ck/Okatama/T6/07
Media Links
Recombinomics Presentations
Recombinomics Publications
Recombinomics Paper at Nature Precedings