Migration of Qinghai H5N1 To Moscow Suburbs
Recombinomics Commentary
February 19, 2007
Vlasov said the virus was probably brought to Moscow by migrating birds from the Caucasus or the Middle East.
"Preliminary data show the virus could have come from the region around Azerbaijan or Iran," the health official said.
Controls were in place limiting movement to and from the five villages where bird flu had been found since Friday, in the Taldom, Domodedovo, Podolsk, Naro-Fominsk and Odintsovo districts, and the Sadovod market would remain closed until further checks had been carried out, he said.
The above comments provide more detail on the H5N1 outbreaks in the suburbs of Moscow. The preliminary data indicate the H5N1 is the Qinghai strain with regional markers seen in Azerbaijan and Iran last season.
Qinghai H5N1 was isolated in both countries in February, 2006. Although all of the H5N1 in Europe, the Middle East, and Africa was the Qinghai strain, the sequences indicated there were multiple introductions from wild birds and the H5N1’s had regional polymorphisms. In many cases these were shared with local low path avian influenza, providing additional data for H5N1 evolution via recombination.
NAMRU-3 has released a number of H5N1 sequences this season. Analysis of the human and bird sequences by Recombinomics demonstrates acquisition of new polymorphisms via recombination. Although the isolates from this season retain most of the regional markers from last season, new polymorphisms are added onto the genetic backgroiund from last season. In Egypt, HA M230I is an example of a “new” polymorphism from two sets of donor sequences, which are fixing M230I in Egypt.
The comments above indicate that the H5N1 in Moscow is following a similar mechanism of evolution by retaining regional polymorphisms from last season, and adding additional markers from this season.
Comments on the H5N1 sequences from two outbreaks in Hungary indocate a similar mechanism of evolution is being seen there, resulting in 2007 H5N1 in Hungary maintaining 99.4% identity with Qinghai isolates in Europe in 2006.
The evolution via recombination allows for tracing of isolates and flight paths of migrating birds carrying new polymorphisms which generate predictions of emerging genotypes based on recombination with dominant genotypes in the region.
The linkage of H5N1 in Moscow to H5N1 in Azerbaijan is cause for concern. In 2006 there were large clusters in Azerbaijan with ties to wild bird de-feathering. H5N1 from patients also had changes in the receptor binding domain such as N186K in Azerbaijan. Recent sequences from Egypt have additional receptor binding domain changes (V223I, S227N, M230I) as well as Tamiflu resistance (N294S), which could create more efficient transmission of a Qinghai H5N1 with Tamiflu resistance markers.
Media sources
Phylogenetic Trees