## Abstract Continued rapid evolution of the influenza A virus is responsible for annual epidemics and occasional pandemics in the Shanghai area. In the present study, the representative strains of A/H1N1 and A/H3N2 influenza viruses isolated in the Shanghai area from 2005 to 2008 were antigenicall
Divergent evolution of hemagglutinin and neuraminidase genes in recent influenza A:H3N2 viruses isolated in Canada
โ Scribed by Yacine Abed; Isabelle Hardy; Yan Li; Guy Boivin
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 73 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0146-6615
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โฆ Synopsis
Abstract
Limited information is available concerning the molecular drift of the influenza neuraminidase (NA) genes. We report on the genetic variability of the NA gene from 31 influenza A:H3N2 viruses isolated in the Province of Quรฉbec (Canada) during the last three flu seasons (1997โ2000). Amino acid substitutions within the NA protein were observed at rates of 1.01% and 0.45% between strains of the 1997โ1998 and 1998โ1999 seasons and between those of the 1998โ1999 and 1999โ2000 seasons, respectively. In most strains (28/31), amino acid changes occurred within at least one of four codons (197, 339, 370, and 401) previously implicated as antigenic sites. The 8 functional and 10 framework residues that compose the catalytic site of the NA enzyme were completely conserved over the study period. All isolates contained the seven conserved asparagineโlinked glycosylation sites found in the NA of the progenitor A/Hong Kong/8/68 strain. In addition, most strains (30/31) had an eighth potential glycosylation site at position 329, whereas a ninth one was found at position 93 in 16 strains. The NA of all strains in this study was related to that of the vaccine strain A/Beijing/353/89, whereas the HA genes of these strains were related to the A/Beijing/32/92 vaccine strain. Thus, it appears that recent influenza strains continue to evolve from a reassortant produced during the cocirculation of the two above variants. Interestingly, some strains whose HA genes were closely related showed significant differences in their NA genes and conversely. This study confirms the importance of analyzing both the NA and the HA genes to assess the evolution of recent influenza epidemic strains. J. Med. Virol. 67:589โ595, 2002. ยฉ 2002 WileyโLiss, Inc.
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