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Assessing Antigenic Drift of Seasonal Influenza A(H3N2) and A(H1N1)pdm09 Viruses.

Tewawong N, Prachayangprecha S, Vichiwattana P, Korkong S, Klinfueng S, Vongpunsawad S, Thongmee T, Theamboonlers A, Poovorawan Y - PLoS ONE (2015)

Bottom Line: Meanwhile, most A(H1N1)pdm09 strains from the 2012-2014 seasons belonged to genetic clades 6A, 6B, and 6C and displayed the dominant epitope mutations at epitopes B and E.Finally, the vaccine efficacy for A(H1N1)pdm09 (79.6-93.4%) was generally higher than that of A(H3N2).These findings further confirmed the accelerating antigenic drift of the circulating influenza A(H3N2) in recent years.

View Article: PubMed Central - PubMed

Affiliation: Center of Excellence in Clinical Virology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

ABSTRACT
Under selective pressure from the host immune system, antigenic epitopes of influenza virus hemagglutinin (HA) have continually evolved to escape antibody recognition, termed antigenic drift. We analyzed the genomes of influenza A(H3N2) and A(H1N1)pdm09 virus strains circulating in Thailand between 2010 and 2014 and assessed how well the yearly vaccine strains recommended for the southern hemisphere matched them. We amplified and sequenced the HA gene of 120 A(H3N2) and 81 A(H1N1)pdm09 influenza virus samples obtained from respiratory specimens and calculated the perfect-match vaccine efficacy using the pepitope model, which quantitated the antigenic drift in the dominant epitope of HA. Phylogenetic analysis of the A(H3N2) HA1 genes classified most strains into genetic clades 1, 3A, 3B, and 3C. The A(H3N2) strains from the 2013 and 2014 seasons showed very low to moderate vaccine efficacy and demonstrated antigenic drift from epitopes C and A to epitope B. Meanwhile, most A(H1N1)pdm09 strains from the 2012-2014 seasons belonged to genetic clades 6A, 6B, and 6C and displayed the dominant epitope mutations at epitopes B and E. Finally, the vaccine efficacy for A(H1N1)pdm09 (79.6-93.4%) was generally higher than that of A(H3N2). These findings further confirmed the accelerating antigenic drift of the circulating influenza A(H3N2) in recent years.

No MeSH data available.


Related in: MedlinePlus

Phylogenetic analysis of the HA1 nucleotide sequences of influenza A(H1N1)pdm09.Sequences from 81 strains isolated in Thailand between 2010 and 2014 (designated A/Thailand/CU) were compared to the reference strains of known clades reported by WHO Influenza Center London (bolded) and the southern hemisphere vaccine strains recommended by WHO (denoted with triangles). Phylogenic tree was generated using maximum likelihood method by HKY+G model. Bootstrap values of 1,000 replicates >50 are indicated at the nodes. Also at the nodes are the signature amino acid changes in different colors according to epitopes. Scale bar represents approximately 0.2% nucleotide difference between close relatives.
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pone.0139958.g002: Phylogenetic analysis of the HA1 nucleotide sequences of influenza A(H1N1)pdm09.Sequences from 81 strains isolated in Thailand between 2010 and 2014 (designated A/Thailand/CU) were compared to the reference strains of known clades reported by WHO Influenza Center London (bolded) and the southern hemisphere vaccine strains recommended by WHO (denoted with triangles). Phylogenic tree was generated using maximum likelihood method by HKY+G model. Bootstrap values of 1,000 replicates >50 are indicated at the nodes. Also at the nodes are the signature amino acid changes in different colors according to epitopes. Scale bar represents approximately 0.2% nucleotide difference between close relatives.

Mentions: To assess the evolution of the A(H1N1)pdm09 during the same period, circulating strains in 2010 (N = 18), 2011 (N = 7), 2012 (N = 5), 2013 (N = 7), and 2014 (N = 44) seasons were also compared to the vaccine and reference sequences (Fig 2). There were distinct phylogenetic groups of A(H1N1)pdm09 strains between 2010 to 2014. Among the A(H1N1)pdm09 strains, 69% belonged to clade 6 viruses, while 31% grouped into clades 1, 4, 5, and 7. The HA1 sequence of A(H1N1)pdm09 viruses isolated in the 2013–2014 season clustered in genetic clades 6B and 6C. Although both sub-clades were related to the A/California/07/2009 vaccine strain (recommended every year since 2010) and shared > 98.2% nucleotide and > 97.4% amino acid sequence homology, they were slightly different from A/California/07/2009 in that they shared D97N and S185T substitutions (S4 Table). Moreover, sub-clade 6B possessed additional K163Q, K283E, and A256T substitutions, while clade 6C possessed V234I, M257V, and K283E substitutions. No changes were observed in the A(H1N1)pdm09 at residues Y98, T133, W150, H180, and Q223, which are conserved and important in the HA receptor binding pocket of the influenza virus [26].


Assessing Antigenic Drift of Seasonal Influenza A(H3N2) and A(H1N1)pdm09 Viruses.

Tewawong N, Prachayangprecha S, Vichiwattana P, Korkong S, Klinfueng S, Vongpunsawad S, Thongmee T, Theamboonlers A, Poovorawan Y - PLoS ONE (2015)

Phylogenetic analysis of the HA1 nucleotide sequences of influenza A(H1N1)pdm09.Sequences from 81 strains isolated in Thailand between 2010 and 2014 (designated A/Thailand/CU) were compared to the reference strains of known clades reported by WHO Influenza Center London (bolded) and the southern hemisphere vaccine strains recommended by WHO (denoted with triangles). Phylogenic tree was generated using maximum likelihood method by HKY+G model. Bootstrap values of 1,000 replicates >50 are indicated at the nodes. Also at the nodes are the signature amino acid changes in different colors according to epitopes. Scale bar represents approximately 0.2% nucleotide difference between close relatives.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594909&req=5

pone.0139958.g002: Phylogenetic analysis of the HA1 nucleotide sequences of influenza A(H1N1)pdm09.Sequences from 81 strains isolated in Thailand between 2010 and 2014 (designated A/Thailand/CU) were compared to the reference strains of known clades reported by WHO Influenza Center London (bolded) and the southern hemisphere vaccine strains recommended by WHO (denoted with triangles). Phylogenic tree was generated using maximum likelihood method by HKY+G model. Bootstrap values of 1,000 replicates >50 are indicated at the nodes. Also at the nodes are the signature amino acid changes in different colors according to epitopes. Scale bar represents approximately 0.2% nucleotide difference between close relatives.
Mentions: To assess the evolution of the A(H1N1)pdm09 during the same period, circulating strains in 2010 (N = 18), 2011 (N = 7), 2012 (N = 5), 2013 (N = 7), and 2014 (N = 44) seasons were also compared to the vaccine and reference sequences (Fig 2). There were distinct phylogenetic groups of A(H1N1)pdm09 strains between 2010 to 2014. Among the A(H1N1)pdm09 strains, 69% belonged to clade 6 viruses, while 31% grouped into clades 1, 4, 5, and 7. The HA1 sequence of A(H1N1)pdm09 viruses isolated in the 2013–2014 season clustered in genetic clades 6B and 6C. Although both sub-clades were related to the A/California/07/2009 vaccine strain (recommended every year since 2010) and shared > 98.2% nucleotide and > 97.4% amino acid sequence homology, they were slightly different from A/California/07/2009 in that they shared D97N and S185T substitutions (S4 Table). Moreover, sub-clade 6B possessed additional K163Q, K283E, and A256T substitutions, while clade 6C possessed V234I, M257V, and K283E substitutions. No changes were observed in the A(H1N1)pdm09 at residues Y98, T133, W150, H180, and Q223, which are conserved and important in the HA receptor binding pocket of the influenza virus [26].

Bottom Line: Meanwhile, most A(H1N1)pdm09 strains from the 2012-2014 seasons belonged to genetic clades 6A, 6B, and 6C and displayed the dominant epitope mutations at epitopes B and E.Finally, the vaccine efficacy for A(H1N1)pdm09 (79.6-93.4%) was generally higher than that of A(H3N2).These findings further confirmed the accelerating antigenic drift of the circulating influenza A(H3N2) in recent years.

View Article: PubMed Central - PubMed

Affiliation: Center of Excellence in Clinical Virology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

ABSTRACT
Under selective pressure from the host immune system, antigenic epitopes of influenza virus hemagglutinin (HA) have continually evolved to escape antibody recognition, termed antigenic drift. We analyzed the genomes of influenza A(H3N2) and A(H1N1)pdm09 virus strains circulating in Thailand between 2010 and 2014 and assessed how well the yearly vaccine strains recommended for the southern hemisphere matched them. We amplified and sequenced the HA gene of 120 A(H3N2) and 81 A(H1N1)pdm09 influenza virus samples obtained from respiratory specimens and calculated the perfect-match vaccine efficacy using the pepitope model, which quantitated the antigenic drift in the dominant epitope of HA. Phylogenetic analysis of the A(H3N2) HA1 genes classified most strains into genetic clades 1, 3A, 3B, and 3C. The A(H3N2) strains from the 2013 and 2014 seasons showed very low to moderate vaccine efficacy and demonstrated antigenic drift from epitopes C and A to epitope B. Meanwhile, most A(H1N1)pdm09 strains from the 2012-2014 seasons belonged to genetic clades 6A, 6B, and 6C and displayed the dominant epitope mutations at epitopes B and E. Finally, the vaccine efficacy for A(H1N1)pdm09 (79.6-93.4%) was generally higher than that of A(H3N2). These findings further confirmed the accelerating antigenic drift of the circulating influenza A(H3N2) in recent years.

No MeSH data available.


Related in: MedlinePlus