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Recombination in H5N1 Wild Bird Flu in Tula Russia
December 1, 2005
The HA and NA sequences from an infected domestic chicken in Tula (A/chicken/Tula/10/2005) have been made available at GenBank. These sequences are closely related to the Russian sequences from Novosibirsk as well as the other H5N1 wild bird sequences from Mongolia and Qinghai Lake. The Tula sequences are from an isolate from last month and clearly shows that migratory birds are responsible for the HPAI H5N1 spread into Europe, including European Russia.
These sequences have a acquired a few polymorphisms from Mongolia. Yunnan, and Hunan, further delineating the intersecting paths of migratory birds and the associated recombinations leading to acquisition of polymorphisms.
The interoduction of HPAI into European Russia also raises the possibility that H5N1 will become endemic to local birds and created more opportunities for additional dual infections and recombinations. The release of four full sets of sequences from tree sparrows in Henin supports this notion. Those sequences are also HPAI H5N1 however the represents older configurations with H5N1 sequences on the outside and H9N2 related sequences on the inside as was found in the 1997 outbreak in Hong Kong. Moreover, there are also shared sequences with LPAI H5N1 found in Japan, Primorie, Mongolia, and northern Europe, especially various H5 isolates from Sweden.
Thus, a variety of H5's are being established along migratory bird pathways. These sequences provide additional genetic diversity via recombination and highlight mechanisms of accelerated genetic diversity linked to the evolution of HPAI H5N1.