Commentary
Vietnamese H5N1 In South Korean Outbreak
Recombinomics Commentary 11:00
May 14, 2008
A government official said a highly pathogenic virus that caused bird flu in North Jeolla Province last month was confirmed to have DNA similar to that of a Vietnamese strain.
Experts predict the nation will likely suffer bird flu throughout the year if it fails to exterminate what they call the "southern-type virus."
The above comments suggest that some or all of the H5N1 in South Korea is a new clade related to H5N1 in Vietnam. This definition is somewhat unclear because there have been two distinct clades in Vietnam previously. In 2004/2005 clade 1 dominated, but more recently clade 2.3 from China (Fujian strain) has become dominated. Therefore, the genetic composition in South Korea is unclear, but several local media stories also refer to a Vietnamese (or southern strain). Clade 1 was noted for its ability to asymptomatically infect ducks and grow to high levels in the duck’s intestine, creating significant control problems.
Genetically, there is also prior evidence for exchanges between Vietnam and South Korea / Japan. The 2003 / 2004 isolates were precursors to clade 2.2 (Qinghai strain), which has become dominant in migratory birds that summer in Siberia and Mongolia. All H5N1 west of China has been clade 2.2 which was also true for South Korea and Japan in the 2006/2007 season.
However, the 2003/2004 isolates form South Korea / Japan had a novel cleavage site RERR_KKR (delected an R), which was subsequently found in northern Vietnam in early 2005. This acquisition was appended onto a clade 1 genetic background, indicating it was acquired by recombination. The change was associated with larger clusters and milder H5N1 cases.
Media reports in South Korea also suggest that the US CDC has confirmed H5N1 in patient(s) in South Korea, as had been previously seen in the soldier that was H5 positive. Korea claimed the soldier was H5N1 “negative” because they couldn’t confirm the N1. However, they did not deny confirmation of H5, which meets the WHO definition of a confirmed case. It seems that the confirmation by the CDC is being withheld, and a Friday meeting is planed to discuss the development.
These developments may be related to recent WHO comments on sharing of research results. The withholding of this information remains hazardous to the world’s health.
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