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Qinghai Nature Reserve - Bird Flu Evolution in Action
Recombinomics Commentary
May 24, 2005
>> The expedient notification by PR China on this outbreak is a most welcome manifestation of transparency, which deserves to be warmly welcomed.
Clearly, the avian influenza A H5N1 virus strain has been demonstrated
(how?) in the affected birds. However, it is rather exceptional of avian
influenza causing acute mass mortality involving 5 different species of
wild birds simultaneously. Other factors, infectious or otherwise, might be
involved and should be ruled out prior to final incrimination of the
demonstrated virus strain as the sole causative agent. - Mod.AS <<
H5N1 infections are generally determined by PCR and with 519 dead birds as potential sources, it seems likely that the 5 species were each infected with H5N1. Although the bar-headed geese winter in India, the nature reserve would seem to offer opportunies for dual infections with H5N1 from several sources. Bird flu vaccine efforts seem to be targeting places west of the animal reserve. The China envoy recalled from Japan is heading to Mongolia, the area that would be crossed by birds migrating north to southern Russia.
H5N1 evolves via recombination, and mixing of viruses from diverse geographical regions would generate new sequences for new seasons. In Thailand the 2004 isolates were stable, but new sequences began to appear in 2005, which also happened in northern Vietnam. The changes are far from random. Recombination is the driver of rapid evolution. The polymerase doesn't make errors preferentially in migrating birds during breeding season.
The annual changes in H5N1 are due to recombination between divergent genotypes, which would be present in animal reserves frequented by a variety of migrating birds from various regions.
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These birds can move H5N1 to the north to southern Russia and to the west and the central-south flyway.
H5N1 is just one bird flight away from a variety of destinations in Asia and Europe.
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