- 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.
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- 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.
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- 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.
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- 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.
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