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Molecular characterization of the HA gene of influenza type B viruses
Author(s) -
Pechirra Pedro,
Nunes Baltazar,
Coelho Anabela,
Ribeiro Carlos,
Gonçalves Paulo,
Pedro Sónia,
Castro Luísa Canto e,
RebelodeAndrade Helena
Publication year - 2005
Publication title -
journal of medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 121
eISSN - 1096-9071
pISSN - 0146-6615
DOI - 10.1002/jmv.20490
Subject(s) - phylogenetic tree , biology , virology , lineage (genetic) , genetics , gene , nucleotide
Nucleotide sequences of the HA1 subunit of influenza B viruses isolated in Portugal between 1994 and 2003 influenza winter seasons were analyzed by the Neighbor‐Joining algorithm and rates of HA1 evolution estimated by linear regression. From 1994 to 2002, all influenza B viruses studied were of the Yamagata lineage. Strains isolated from 1994 to 1996, 1996 to 1999, and 1999 to 2002 revealed a high similarity with B/Beijing/184/93, B/Yamanashi/166/98, and B/Sichuan/379/99, respectively, and strains isolated during 1994–1995, 1996–1997, and 1998–1999 clustered in more than one branch of the phylogenetic tree. Victoria‐related strains reappeared during 2002/2003 and formed only one branch in the phylogenetic tree revealing a closer relationship to B/Shandong/7/97. Evolutionary rates for strains from the Yamagata lineage were estimated as 3.82 × 10 −3 nucleotides/site/year and 2.62 × 10 −3 nucleotides/site/year for Victoria‐related strains. In order to identify putative influenza B HA1 codons under selective pressure, a codon‐substitution model for heterogeneous selective pressure at amino acid sites was used. A percentage of 97.3% of codons under negative selective pressure and 2.7% of codons under positive selective pressure (ω = dN/dS = 2.65) were estimated, with posterior probability higher than 0.90. Amino acid sites 75, 197, and 199 were found more likely to be under positive selective pressure. J. Med. Virol. 77:541–549, 2005. © 2005 Wiley‐Liss, inc.