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Genetic diversity of the 2009 pandemic influenza A(H1N1) viruses in Finland.

Ikonen N, Haanpää M, Rönkkö E, Lyytikäinen O, Kuusi M, Ruutu P, Kallio-Kokko H, Mannonen L, Lappalainen M, Ziegler T, Julkunen I - PLoS ONE (2010)

Bottom Line: During the next three months almost all infections were found from patients who had recently traveled abroad.Most amino acid changes in HA and NA molecules accumulated on the surface of the molecule and were partly located in antigenic sites.All Finnish pandemic viruses were sensitive to oseltamivir having the amino acid histidine at residue 275 of the neuraminidase molecule.

View Article: PubMed Central - PubMed

Affiliation: Viral Infections Unit, Department of Vaccination and Immune Protection, National Institute for Health and Welfare THL, Helsinki, Finland. niina.ikonen@thl.fi

ABSTRACT

Background: In Finland, the first infections caused by the 2009 pandemic influenza A(H1N1) virus were identified on May 10. During the next three months almost all infections were found from patients who had recently traveled abroad. In September 2009 the pandemic virus started to spread in the general population, leading to localized outbreaks and peak epidemic activity was reached during weeks 43-48.

Methods/results: The nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes from viruses collected from 138 patients were determined. The analyzed viruses represented mild and severe infections and different geographic regions and time periods. Based on HA and NA gene sequences, the Finnish pandemic viruses clustered in four groups. Finnish epidemic viruses and A/California/07/2009 vaccine virus strain varied from 2-8 and 0-5 amino acids in HA and NA molecules, respectively, giving a respective maximal evolution speed of 1.4% and 1.1%. Most amino acid changes in HA and NA molecules accumulated on the surface of the molecule and were partly located in antigenic sites. Three severe infections were detected with a mutation at HA residue 222, in two viruses with a change D222G, and in one virus D222Y. Also viruses with change D222E were identified. All Finnish pandemic viruses were sensitive to oseltamivir having the amino acid histidine at residue 275 of the neuraminidase molecule.

Conclusions: The Finnish pandemic viruses were quite closely related to A/California/07/2009 vaccine virus. Neither in the HA nor in the NA were changes identified that may lead to the selection of a virus with increased epidemic potential or exceptionally high virulence. Continued laboratory-based surveillance of the 2009 pandemic influenza A(H1N1) is important in order to rapidly identify drug resistant viruses and/or virus variants with potential ability to cause severe forms of infection and an ability to circumvent vaccine-induced immunity.

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Related in: MedlinePlus

Surveillance data from May 4, 2009 to June 20, 2010 in Finland.The weekly numbers of laboratory confirmed infections of the 2009 pandemic influenza A(H1N1) viruses reported to the National Infectious Disease Registry from week 19 in 2009 to week 24 in 2010.
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pone-0013329-g001: Surveillance data from May 4, 2009 to June 20, 2010 in Finland.The weekly numbers of laboratory confirmed infections of the 2009 pandemic influenza A(H1N1) viruses reported to the National Infectious Disease Registry from week 19 in 2009 to week 24 in 2010.

Mentions: The novel influenza A(H1N1) virus of swine-origin emerged in humans in spring 2009. After initial reports from Mexico and the United States (USA) the virus spread rapidly to many countries. In Finland the first two infections caused by the 2009 pandemic influenza A(H1N1) virus were identified on May 10 from two individuals returning from Mexico. Between May and July 2009 nearly 90% of infections, and in August approximately 60% of infections, the 2009 pandemic influenza A(H1N1) virus was found in individuals who had recently returned from abroad. During September the first local outbreaks were recorded in garrisons and in schools in different parts of the country. In the beginning of October, the virus started to spread efficiently in the general population. Peak epidemic activity was reached late October and early November in northern, and two weeks later in southern parts of the country. Mid-December 2009 the first epidemic caused by the novel H1N1 pandemic virus was practically over in Finland (Figure 1).


Genetic diversity of the 2009 pandemic influenza A(H1N1) viruses in Finland.

Ikonen N, Haanpää M, Rönkkö E, Lyytikäinen O, Kuusi M, Ruutu P, Kallio-Kokko H, Mannonen L, Lappalainen M, Ziegler T, Julkunen I - PLoS ONE (2010)

Surveillance data from May 4, 2009 to June 20, 2010 in Finland.The weekly numbers of laboratory confirmed infections of the 2009 pandemic influenza A(H1N1) viruses reported to the National Infectious Disease Registry from week 19 in 2009 to week 24 in 2010.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2958116&req=5

pone-0013329-g001: Surveillance data from May 4, 2009 to June 20, 2010 in Finland.The weekly numbers of laboratory confirmed infections of the 2009 pandemic influenza A(H1N1) viruses reported to the National Infectious Disease Registry from week 19 in 2009 to week 24 in 2010.
Mentions: The novel influenza A(H1N1) virus of swine-origin emerged in humans in spring 2009. After initial reports from Mexico and the United States (USA) the virus spread rapidly to many countries. In Finland the first two infections caused by the 2009 pandemic influenza A(H1N1) virus were identified on May 10 from two individuals returning from Mexico. Between May and July 2009 nearly 90% of infections, and in August approximately 60% of infections, the 2009 pandemic influenza A(H1N1) virus was found in individuals who had recently returned from abroad. During September the first local outbreaks were recorded in garrisons and in schools in different parts of the country. In the beginning of October, the virus started to spread efficiently in the general population. Peak epidemic activity was reached late October and early November in northern, and two weeks later in southern parts of the country. Mid-December 2009 the first epidemic caused by the novel H1N1 pandemic virus was practically over in Finland (Figure 1).

Bottom Line: During the next three months almost all infections were found from patients who had recently traveled abroad.Most amino acid changes in HA and NA molecules accumulated on the surface of the molecule and were partly located in antigenic sites.All Finnish pandemic viruses were sensitive to oseltamivir having the amino acid histidine at residue 275 of the neuraminidase molecule.

View Article: PubMed Central - PubMed

Affiliation: Viral Infections Unit, Department of Vaccination and Immune Protection, National Institute for Health and Welfare THL, Helsinki, Finland. niina.ikonen@thl.fi

ABSTRACT

Background: In Finland, the first infections caused by the 2009 pandemic influenza A(H1N1) virus were identified on May 10. During the next three months almost all infections were found from patients who had recently traveled abroad. In September 2009 the pandemic virus started to spread in the general population, leading to localized outbreaks and peak epidemic activity was reached during weeks 43-48.

Methods/results: The nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes from viruses collected from 138 patients were determined. The analyzed viruses represented mild and severe infections and different geographic regions and time periods. Based on HA and NA gene sequences, the Finnish pandemic viruses clustered in four groups. Finnish epidemic viruses and A/California/07/2009 vaccine virus strain varied from 2-8 and 0-5 amino acids in HA and NA molecules, respectively, giving a respective maximal evolution speed of 1.4% and 1.1%. Most amino acid changes in HA and NA molecules accumulated on the surface of the molecule and were partly located in antigenic sites. Three severe infections were detected with a mutation at HA residue 222, in two viruses with a change D222G, and in one virus D222Y. Also viruses with change D222E were identified. All Finnish pandemic viruses were sensitive to oseltamivir having the amino acid histidine at residue 275 of the neuraminidase molecule.

Conclusions: The Finnish pandemic viruses were quite closely related to A/California/07/2009 vaccine virus. Neither in the HA nor in the NA were changes identified that may lead to the selection of a virus with increased epidemic potential or exceptionally high virulence. Continued laboratory-based surveillance of the 2009 pandemic influenza A(H1N1) is important in order to rapidly identify drug resistant viruses and/or virus variants with potential ability to cause severe forms of infection and an ability to circumvent vaccine-induced immunity.

Show MeSH
Related in: MedlinePlus