Paradigm Shift Intervention Monitoring
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Commentary
H7N9 In Shaoxing Zhejiang Has PB2 D87N
Recombinomics Commentary
21:00
October 18, 2013
The two sets of sequences confirmed that the lineages for all 8 gene segments matched the lineages for the consensus sequence for cases in Shanghai and adjacent provinces. The H7 sequence by both labs was identical and included Q226L, as expected. However, the sequences also contained Q222P, which is adjacent to the receptor binding domain.
However, the PB2 sequences differed. A/Zhejiang/22/2013 had an avian sequence which lacked mammalian adaptation markers. In contrast, A/Zhejiang/DTID-ZJU05/2013 had D60N and D87N. The latter is a mammalian adaption which produces an increased polymerase activity at lower temperatures (33 C), consistent with a higher viral load in a human nose in the winter. This temperature sensitive activity is also found in PB2 with E627K.
The CDC sequences suggests that isolates with higher levels of D87N will more efficiently transmit human to human.
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