Uva Lake Strain of H5N1 in Northeastern Germany
Recombinomics Commentary
December 17, 2007
The samples were immediately transferred to the OIE (World Organization for Animal Health) and National Reference Laboratory for Avian Influenza at the Friedrich-Loeffler-Institut. Real-time RT-PCR specific for Qinghai-like strains of HPAIV (Hoffmann et al., 2007) confirmed the presence of HPAIV H5N1 in these samples. Preliminary results of the sequencing analysis of the HA-gene showed a close relationship to HPAIV H5N1 isolates detected earlier in 2007 in Germany (HPAIV H5N1 subclade 2.2.3; Starick et al., 2007).
The above comments on initial sequence data from the H5N1 isolates from Germany indicate that the sequences are related to the Uva Lake sequences detected throughout Europe since the summer. These results are not a surprise. The sequences were first reported in a massive wild bird outbreak in the summer of 2006. The number of dead wild birds was on a par with the Qinghai Lake outbreak in central China. Qinghai lake is the largest lake in China, while Uva Lake is the largest lake in Mongolia. However, unlike the 2005 outbreak which was followed by the detection of the Qinghai strain in over 50 countries west of China in the following 12 months, the Uva Lake strain was only reported in Kuwait prior to the summer of 2007.
However, in the summer of 2007, the Uva Lake strain was first reported at a poultry outbreak in the Czech Republic which was quickly followed by detection in wild birds in the Czech Republic and Germany. The detection in Germany spread to multiple locations in central and southern Germany. Although all outbreaks were related to Uva Lake, each location represented an independent introduction.
These outbreaks were followed by wild bird outbreaks in France and domestic poultry in Germany. In the fall H5N1 was reported in poultry and wild birds in Krasnodar. The whooper swan and chicken sequences from Krasnodar were published and were 99.95% identical. The were also the Uva Lake sub-clade and were closely related to sequences from three of the wild bird outbreaks in Germany.
More recently, the sequences from domestic poultry outbreaks in England were described, and these sequences were also Uva Lake sequences closely related to the earlier outbreaks. The data described by the Fredrich Loeffler researchers indicates H5N1 in northeastern Germany is also the Uva Lake strain, which suggest that the recent outbreaks in adjacent Poland will also be the Uva Lake strain.
These data support the replacement of the various Qinghai sub-clades circulating in Europe between 2005 and 2007 with the Uva Lake strain, which has been the only strain reported in Europe since the summer. This replacement supports a influx via wild birds beginning in the fall of 2006, but circulating undetected throughout Europe until the summer of 2007.
The detection in the summer, followed by multiple reports in recent weeks predicts H5N1 infections in Europe will be widespread inn the upcoming months, and the infections will be almost exclusively the Uva Lake strain.
Similar sequences in Pakistan would not be a surprise.
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