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Commentary
Another H7N9 Zhejiang Case Raises Concerns
Recombinomics Commentary
12:15
October 23, 2013
the patient was seriously ill, hospitals are in active treatment
The above translation describes the second confirmed H7N9 bird flu case (67M) in Zhejiang Province in a week. Like the earlier case (35M), the patient is in critical condition. These two cases cluster in time and space (see map) and raise concerns that the 2013/2014 flu season in northern China will lead to a dramatic increase in cases. In the spring, the vast majority of cases were concentrated in the greater Shanghai metropolitan area, with the most reported cases in Zhejiang province (see earlier map).
Sequences from the first case were promptly released by the Zhejiang University and Zhejiang CDC (A/Zhejiang/DTID-ZJU05/2013 and A/Zheijiang/22/2013, respectively). The H7 from the October 14 collection had Q226L and both sequences were identical. The H7, like the other 7 gene segments produced a constellation of sequences that matched the majority of cases in the spring.
However, the Zhejiang CDC PB2 sequence had no mammalian adaption markers, such as E627K, which was present in the vast majority of human PB2 sequences. However, the Zhejiang University PB2 sequence had two non-synonymous changes, including D87N.
D87N like E627K are associated with increased polymerase activity at lower temperatures (33 C) which is a strong selection marker associated with increased mammalian transmission.
The temporal and geographic clustering of the two recent H7N9 cases raises concerns that many additional H7N9 cases will be reported in the near term.
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