Emerged HA and NA Mutants of the Pandemic Influenza H1N1 Viruses with Increasing Epidemiological Significance in Taipei and Kaohsiung, Taiwan, 2009-10
Resource
PLoS One, 7(2)
Journal
PLoS One
Journal Volume
7
Journal Issue
2
Pages
-
Date Issued
2012
Date
2012
Author(s)
Kao, Chuan-Liang
Chan, Ta-Chien
Tsai, Chu-Han
Chu, Kuan-Ying
Chuang, Shu-Fang
Lee, Chang-Chun
Li, Zheng-Rong Tiger
Wu, Ko-Wen
Chang, Luan-Yin
Shen, Yea-Huei
Huang, Li-Min
Lee, Ping-Ing
Yang, ChingLai
Compans, Richard
Rouse, Barry T.
King, Chwan-Chuen
Abstract
The 2009 influenza pandemic provided an opportunity to observe dynamic changes of the hemagglutinin (HA) and neuraminidase (NA) of pH1N1 strains that spread in two metropolitan areas - Taipei and Kaohsiung. We observed cumulative increases of amino acid substitutions of both HA and NA that were higher in the post-peak than in the pre-peak period of the epidemic. About 14.94% and 3.44% of 174 isolates had one and two amino acids changes, respective, in the four antigenic sites. One unique adaptive mutation of HA2 (E374K) was first detected three weeks before the epidemic peak. This mutation evolved through the epidemic, and finally emerged as the major circulated strain, with significantly higher frequency in the post-peak period than in the pre-peak (64.65% vs 9.28%, p<0.0001). E374K persisted until ten months post-nationwide vaccination without further antigenic changes (e. g. prior to the highest selective pressure). In public health measures, the epidemic peaked at seven weeks after oseltamivir treatment was initiated. The emerging E374K mutants spread before the first peak of school class suspension, extended their survival in high-density population areas before vaccination, dominated in the second wave of class suspension, and were fixed as herd immunity developed. The tempospatial spreading of E374K mutants was more concentrated during the post-peak (p = 0.000004) in seven districts with higher spatial clusters (p<0.001). This is the first study examining viral changes during the naive phase of a pandemic of influenza through integrated virological/serological/clinical surveillance, tempo-spatial analysis, and intervention policies. The vaccination increased the percentage of E374K mutants (22.86% vs 72.34%, p<0.001) and significantly elevated the frequency of mutations in Sa antigenic site (2.36% vs 23.40%, p<0.001). Future pre-vaccination public health efforts should monitor amino acids of HA and NA of pandemic influenza viruses isolated at exponential and peak phases in areas with high cluster cases.
SDGs
File(s)![Thumbnail Image]()
Loading...
Name
index.html
Size
23.18 KB
Format
HTML
Checksum
(MD5):84333135944ed7a51c1a8f33483558bb