Commentary
Shanxi
H5N1 Clade 7 Changes Raise Pandemic Concerns
Recombinomics Commentary
20:31
February 24, 2009
The new interest in the Shanxi sequence by the National Labs at Harbin adds to the circumstantial evidence that most or all of the six confirmed cases not discussed in the recent WHO report on H5N1 vaccine targets are clade 7, which was also reported for the Jiangsu poultry outbreak in China at the end of the year.
Although the WHO report did not discuss clade 7 in China, the variation in clade 7 in Vietnam was discussed because of the low cross reactivity between 2008 clade 7 isolates. The reduced cross reactivity between clade 7 isolates from the same country and year signals rapid evolution of clade 7, and the limited cross reactivity with antisera directed against clade 1 or clade 2 increases concerns.
The concerns regarding the rapid evolution of clade 7 in Vietnam are increased by the failure of WHO to discuss the six confirmed cases in China, including the Beijing isolate. A/Beijing/1/2009, which was from a fatal infection that began just after the clade 7 outbreak in Jiangsu.
Moreover, the sharing of polymorphisms between vaccine resistant clade 7 in China, and vaccine resistant clade 2.2 in Egypt raises concerns that these polymorphisms are being exported from China via migratory birds, contributing to worldwide vaccine failure.
Release of the 2009 human H5N1 sequences in China, Vietnam, and Egypt would be useful.
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