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Commentary
Clade 2.3.2.1
In Fatal H5N1
Case In Shenzhen China
Recombinomics Commentary 21:20
January 1, 2012
the results show that virus is adamantane class of drugs are more sensitive but resistance to Tamiflu, the role of drugs still under study
The above translation indicates the H5N1 from the fatal case In Shenzhen, China is clade 2.3.2.1, which is common in wild birds. Between December and February, Hong Kong typically finds clade 2.3.2.1 in wild birds. A clade 2.3.2.1 case was identified in Hubei last year, and WHO has selected that isolate, A/Hubei/1/2010 as a pandemic vaccine target. Last November an H5N1 case was also identified in Hong Kong, A/Hong Kong/6841/2010). Both isolates are in the phylogenetic tree in figure 3 in the WHO vaccine update. As seen in the top 100 matches for the Hubei isolate (here) or the Hong Kong isolate (here), wild bird isolate are closely related, although the Hong Kong isolate is closer to sequences from Laos.
Both of the human isolates from 2010 had receptor binding domain changes V223I, D225G, M230I, which are common in wild bird sequences in eastern Asia, and were also in the Gharbya cluster in Egypt in 2006.
The 2010 cases in China were wild type at positions 274 (275) and 294 in NA and therefore susceptible to Tamiflu (oseltamivir).
Although the translation suggests the latest case is wild type at HA positions 226 and 228, but changes at positions 223, 225, and 230 raise concerns that more efficient transmission can be achieved by changes at additional positions.
Release of the sequences from the Shenzhen cases, as well as those that led to airborne transmission in ferrets would be useful.
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