Commentary
H5N1 Rostov Rook Matches Poultry and Wild Birds
Recombinomics Commentary 23:37
June 24, 2008
Full sequences from a rook, A/rook/Rostov-on-Don/26/2007, linked to the December, 2007 outbreak at Gulyay-Borisovskaya in Rostov was released at Genbank. The sequences were virtually identical to earlier sequences from the outbreak (A/chicken/Rostov-on-Don/35/2007, A/pigeon/Rostov-on-Don/6/2007, A/muscovy duck/Rostov-on-Don/51/2007, A/starling/Rostov-on-Don/39/07), which were made public four months ago. The delay in the release of the rook sequences may reflect lower levels of RNA in the rook isolates, leading to technical issues.
The outbreak was recently described in a presentation by Victor Irza on April 9. 2008 in Brussels on H5N1 in Russia, which included details showing the sequence of infections at the farm, as well as the locations of 7 dead birds in the city, and 7 positive cloacal swabs (see satellite map).
Included were pictures of rooks surrounding the farm, raising the possibility that the rooks were the source of the H5N1. The match in the sequences that were just released demonstrated the identity between the rooks sequence and other wild birds and poultry associated with the outbreak.
The identity in the multiple isolates from multiple wild bird species demonstrates how well sequences are conserved when the are linked to a common source. This level of identity is in marked contrast to difference between sequences from multiple locations within a country, such as the H5N1 sequences from Germany over the summer, as well as sequences collected in the Czech Republic. The differences demonstrate independent wild bird introductions, which were also seen in the sequences from the mute swans at the swannery in England. Although the report on that outbreak suggested the H5N1 was from a common source, the sequence diversity clearly indicated that the H5N1 was from multiple sources and was endemic to the wild swan population in the area.
The data from the rook also raise the possibility that H5N1 carriers, which can readily cause H5N1 in a variety of wild bird and domestic poultry species, can be infected at RNA levels which are near the limits of detection.
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