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Positive selection on hemagglutinin and neuraminidase genes of H1N1 influenza viruses.

Li W, Shi W, Qiao H, Ho SY, Luo A, Zhang Y, Zhu C - Virol. J. (2011)

Bottom Line: We also found evidence of strong selection acting on the seasonal human H1N1 isolates.A site-by-site analysis revealed that the positively selected sites were located in both of the cleaved products of HA (HA1 and HA2), as well as NA.Moreover, some sites were also associated with glycosylation and receptor-binding ability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT

Background: Since its emergence in March 2009, the pandemic 2009 H1N1 influenza A virus has posed a serious threat to public health. To trace the evolutionary path of these new pathogens, we performed a selection-pressure analysis of a large number of hemagglutinin (HA) and neuraminidase (NA) gene sequences of H1N1 influenza viruses from different hosts.

Results: Phylogenetic analysis revealed that both HA and NA genes have evolved into five distinct clusters, with further analyses indicating that the pandemic 2009 strains have experienced the strongest positive selection. We also found evidence of strong selection acting on the seasonal human H1N1 isolates. However, swine viruses from North America and Eurasia were under weak positive selection, while there was no significant evidence of positive selection acting on the avian isolates. A site-by-site analysis revealed that the positively selected sites were located in both of the cleaved products of HA (HA1 and HA2), as well as NA. In addition, the pandemic 2009 strains were subject to differential selection pressures compared to seasonal human, North American swine and Eurasian swine H1N1 viruses.

Conclusions: Most of these positively and/or differentially selected sites were situated in the B-cell and/or T-cell antigenic regions, suggesting that selection at these sites might be responsible for the antigenic variation of the viruses. Moreover, some sites were also associated with glycosylation and receptor-binding ability. Thus, selection at these positions might have helped the pandemic 2009 H1N1 viruses to adapt to the new hosts after they were introduced from pigs to humans. Positive selection on position 274 of NA protein, associated with drug resistance, might account for the prevalence of drug-resistant variants of seasonal human H1N1 influenza viruses, but there was no evidence that positive selection was responsible for the spread of the drug resistance of the pandemic H1N1 strains.

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Selection pressure on NA genes from different clusters. Selection pressures for the global ω of NA genes of each cluster. Error bar shows 95% confidence interval.
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Figure 2: Selection pressure on NA genes from different clusters. Selection pressures for the global ω of NA genes of each cluster. Error bar shows 95% confidence interval.

Mentions: Global ω values showed similar results for both HA and NA. The global ω values were below 1.0 for all five clusters, which indicates that there is no detectable positive selection on the gene as a whole (Figures 1 and 2). The ω values for human strains were higher than those for viruses from other hosts. In particular, the ω values of the pandemic 2009 viruses were the highest. ω values for the seasonal human H1N1 and the pandemic 2009 H1N1 lineages were higher than those for viruses from Eurasian and North American swine which, in turn, were similar to each other. Avian strains yielded the lowest ω value.


Positive selection on hemagglutinin and neuraminidase genes of H1N1 influenza viruses.

Li W, Shi W, Qiao H, Ho SY, Luo A, Zhang Y, Zhu C - Virol. J. (2011)

Selection pressure on NA genes from different clusters. Selection pressures for the global ω of NA genes of each cluster. Error bar shows 95% confidence interval.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3094300&req=5

Figure 2: Selection pressure on NA genes from different clusters. Selection pressures for the global ω of NA genes of each cluster. Error bar shows 95% confidence interval.
Mentions: Global ω values showed similar results for both HA and NA. The global ω values were below 1.0 for all five clusters, which indicates that there is no detectable positive selection on the gene as a whole (Figures 1 and 2). The ω values for human strains were higher than those for viruses from other hosts. In particular, the ω values of the pandemic 2009 viruses were the highest. ω values for the seasonal human H1N1 and the pandemic 2009 H1N1 lineages were higher than those for viruses from Eurasian and North American swine which, in turn, were similar to each other. Avian strains yielded the lowest ω value.

Bottom Line: We also found evidence of strong selection acting on the seasonal human H1N1 isolates.A site-by-site analysis revealed that the positively selected sites were located in both of the cleaved products of HA (HA1 and HA2), as well as NA.Moreover, some sites were also associated with glycosylation and receptor-binding ability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT

Background: Since its emergence in March 2009, the pandemic 2009 H1N1 influenza A virus has posed a serious threat to public health. To trace the evolutionary path of these new pathogens, we performed a selection-pressure analysis of a large number of hemagglutinin (HA) and neuraminidase (NA) gene sequences of H1N1 influenza viruses from different hosts.

Results: Phylogenetic analysis revealed that both HA and NA genes have evolved into five distinct clusters, with further analyses indicating that the pandemic 2009 strains have experienced the strongest positive selection. We also found evidence of strong selection acting on the seasonal human H1N1 isolates. However, swine viruses from North America and Eurasia were under weak positive selection, while there was no significant evidence of positive selection acting on the avian isolates. A site-by-site analysis revealed that the positively selected sites were located in both of the cleaved products of HA (HA1 and HA2), as well as NA. In addition, the pandemic 2009 strains were subject to differential selection pressures compared to seasonal human, North American swine and Eurasian swine H1N1 viruses.

Conclusions: Most of these positively and/or differentially selected sites were situated in the B-cell and/or T-cell antigenic regions, suggesting that selection at these sites might be responsible for the antigenic variation of the viruses. Moreover, some sites were also associated with glycosylation and receptor-binding ability. Thus, selection at these positions might have helped the pandemic 2009 H1N1 viruses to adapt to the new hosts after they were introduced from pigs to humans. Positive selection on position 274 of NA protein, associated with drug resistance, might account for the prevalence of drug-resistant variants of seasonal human H1N1 influenza viruses, but there was no evidence that positive selection was responsible for the spread of the drug resistance of the pandemic H1N1 strains.

Show MeSH
Related in: MedlinePlus