Selection pressure on the hemagglutinin gene of Influenza A (H1N1) virus: adaptation to human and swine hosts in Asia

Xu, Zhiwei; Zhou, Ruifang; Jin, Meilin; Chen, H

doi:10.4149/av_2010_02_113

Cited by 2 publications

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“…For the H1 subtype in swine the nucleotide substitution rates have been estimated to range between 1.9-4.4 × 10 −3 per site per year [11,[30][31][32][33], whereas the nucleotide substitution rate of the swine H3 subtype has been documented to be as high as 6 × 10 −3 per site per year [34]. While the highest rates are comparable to that of human H1 subtypes, the selection pressure expressed as the ratio of nonsynonymous to synonymous mutations has been found to be lower in swine compared to humans [11,22,35,36]. However, a very recent study revealed similar rates of synonymous and non-synonymous nucleotide substitutions within the swine H1 lineages 1B and 1C compared to that of human IAV, when investigating the genetic drift of swIAV sampled between 2003-2015 in Germany [37].…”

Section: Introductionmentioning

confidence: 99%

Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses

Ryt-Hansen

Pedersen

Larsen

et al. 2020

Viruses

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The degree of antigenic drift in swine influenza A viruses (swIAV) has historically been regarded as minimal compared to that of human influenza A virus strains. However, as surveillance activities on swIAV have increased, more isolates have been characterized, revealing a high level of genetic and antigenic differences even within the same swIAV lineage. The objective of this study was to investigate the level of genetic drift in one enzootically infected swine herd over one year. Nasal swabs were collected monthly from sows (n = 4) and piglets (n = 40) in the farrowing unit, and from weaners (n = 20) in the nursery. Virus from 1–4 animals were sequenced per month. Analyses of the sequences revealed that the hemagglutinin (HA) gene was the main target for genetic drift with a substitution rate of 7.6 × 10−3 substitutions/site/year and evidence of positive selection. The majority of the mutations occurred in the globular head of the HA protein and in antigenic sites. The phylogenetic tree of the HA sequences displayed a pectinate typology, where only a single lineage persists and forms the ancestor for subsequent lineages. This was most likely caused by repeated selection of a single immune-escape variant, which subsequently became the founder of the next wave of infections.

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Section: Introductionmentioning

confidence: 99%

Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses

Ryt-Hansen

Pedersen

Larsen

et al. 2020

Viruses

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Emerging Antigenic Variants at the Antigenic Site Sb in Pandemic A(H1N1)2009 Influenza Virus in Japan Detected by a Human Monoclonal Antibody

et al. 2013

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The swine-origin pandemic A(H1N1)2009 virus, A(H1N1)pdm09, is still circulating in parts of the human population. To monitor variants that may escape from vaccination specificity, antigenic characterization of circulating viruses is important. In this study, a hybridoma clone producing human monoclonal antibody against A(H1N1)pdm09, designated 5E4, was prepared using peripheral lymphocytes from a vaccinated volunteer. The 5E4 showed viral neutralization activity and inhibited hemagglutination. 5E4 escape mutants harbored amino acid substitutions (A189T and D190E) in the hemagglutinin (HA) protein, suggesting that 5E4 recognized the antigenic site Sb in the HA protein. To study the diversity of Sb in A(H1N1)pdm09, 58 viral isolates were obtained during the 2009/10 and 2010/11 winter seasons in Osaka, Japan. Hemagglutination-inhibition titers were significantly reduced against 5E4 in the 2010/11 compared with the 2009/10 samples. Viral neutralizing titers were also significantly decreased in the 2010/11 samples. By contrast, isolated samples reacted well to ferret anti-A(H1N1)pdm09 serum from both seasons. Nonsynonymous substitution rates revealed that the variant Sb and Ca2 sequences were being positively selected between 2009/10 and 2010/11. In 7,415 HA protein sequences derived from GenBank, variants in the antigenic sites Sa and Sb increased significantly worldwide from 2009 to 2013. These results indicate that the antigenic variants in Sb are likely to be in global circulation currently.

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Selection pressure on the hemagglutinin gene of Influenza A (H1N1) virus: adaptation to human and swine hosts in Asia

Cited by 2 publications

References 0 publications

Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses

Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses

Emerging Antigenic Variants at the Antigenic Site Sb in Pandemic A(H1N1)2009 Influenza Virus in Japan Detected by a Human Monoclonal Antibody

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