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H5N1 Bird Flu at Qinghai Lake is Amantadine Sensitive
July 20, 2005
The H5N1 Qinghai Lake isolates described in Nature are listed below. There are 12 isolates from Qinghai Lake. 10 are bar-headed geese and the other two are a brown-headed gull and a great black-headed gull. Since the WHO report on their Qinghai Lake visit indicated only 12 birds had been tested for H5N1, it seems likely that these are the twelve and the four isolates in Science duplicate four of these isolates. In addition there are eight 2005 isolates from four other provinces in southeastern China, supporting third party reports of widespread H5N1 infections in China in 2005, although prior to the Qinghai report of May 21, there were no 2005 reports by China on H5N1.
Earlier media reports had expressed concern that the Amantadine resistant mutations in isolates from Vietnam and Thailand were linked to Amantadine use in China. The sequences at GenBank did not support the speculation because no H5N1 sequences outside of Vietnam and Thailand had the L26I mutation and only a small percentage of isolates from China had the S31N polymorphism.
Thus, as expected the Qinghai isolates were wild type at both positions and therefore sensitive to Amantadine. The S31N polymorphism was found only in isolate 1621 from Shantou. The Yunnan isolates had the V28I polymorphism and the Hunan isolates matched a Jilin isolate.
The Nature and Science papers cited the high virulence of the Qinghai isolates and third party reports describe human fatalities in Qinghai Province due to the infections by a strain called RK7, which would appear to be the 12 Qinghai isolates listed below
Since most of the Qinghai Lake birds will leave Qinghai in the next few weeks, there is concern that H5N1 similar to the isolates below will cause human or bird infections at locations where they winter. For M2 all 12 of the isolates were virtually identical and sensitive to Amantadine and Rimantadine based on wild type sequences in the region that encodes the ion channel in M2.
Below are the 20 2005 H5N1 isolates available at GenBank.
A/Great Black-headed Gull/Qinghai/2/05(H5N1)