More H5N1 Vaccine Resistance in Egypt
Recombinomics Commentary 21:49
April 29, 2008
Two H5N1 HA sequences from NAMRU-3 are being released at Genbank, A/chicken/Egypt/9402NAMRU-3/CLEVB213/2007 and A/chicken/Egypt/9403NAMRU-3/CLEVB214/2007. Both sequences are from isolates from Sharqiya and are closely related to the vaccine resistant sequences from Egypt and Israel.
The earlier isolates were from vaccinated flocks and had a large number of non-synonymous changes, suggesting the changes were in response to selection pressure linked to the vaccine(s). The changes included M230V, which is adjacent to the receptor binding domain. In addition to the changes in HA, the PB2 from the Israeli isolate had acquired a number of human polymorphisms, raising additional concerns.
These additional sequences from NAMRU-3 provide additional evidence for the emerging dominance of this strain, which will present vaccine problems due to the increased genetic diversity in Egypt and surrounding areas. Recent isolates from Saudi Arabia and Kuwait include clade 2.2.3 introductions to the region, and many of these polymorphisms have been appended onto the clade 2.2.1 genetic background in Egypt.
Recent migration through Egypt, which is located at the intersection of two major flyways will bring added diversity which will be appended onto the 2.2.1 genetic background via recombination.
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