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Commentary
Absence of
E627K in H7N9 Zhejiang Critical Case
Recombinomics
Commentary 20:10
April 18, 2013
However, in contrast to the four prior human sequences, (A/Shanghai/1/2013, A/Shanghai/2/2013, A/Anhui/1/2013, A/Hangzhou/1/2013), the Zhejiang PB2 sequence does not have E627K. Instead position 627 has an E, as seen in the three prior sequences from avian sources, a pigeon (A/Pigeon/Shanghai/S1069/2013), a chicken (A/Chicken/Shanghai/S1053/2013), and an environment sample (A/Environment/Shanghai/S1088/2013) . The avian H7 sequences had Q226L and two of the H7 sequences are closely related to the four most recent human sequences.
In addition, the Zhejiang human PA sequence is more closely related to a 2011 Zhejiang H9N2 bird flu chicken sequence, A/chicken/Zhejiang/607/2011, suggesting that the human case had a direct or indirect linkage to sequences circulating in poultry.
The age of the patient was not released, but the first five cases from Zhejiang were fatal or designated as critical or severe (see map).
It is likely that the above sequence came from a critical case (67M) who was retired (surname Yang), who developed symptoms on March 25 and was transferred to The First Affiliated Hospital, College of Medicine, Zhejiang University on April 2, the day prior to sample collection.
Although the clinical presentation of the H7N9 cases was assumed to be influenced by the E627K in the first 4 sequences (which were from fatal cases), the absence of E627K in the Zhejian sequences raises concerns that other genetic changes, such as Q226L, can produce severe cases (and Q226L was in all three avian H7 sequences).
Release of additional human and avian H7N9 sequences would be useful.
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