Assessing antigenic drift and phylogeny of influenza A (H1N1) pdm09 virus in Kenya using HA1 sub-unit of the hemagglutinin gene

Although oseltamivir-resistant pandemic influenza A(H1N1)pdm09 is uncommon in immunocompetent individuals, a recent report from Newcastle, Australia, showed the first sustained community spread, from June to August 2011, of oseltamivir-resistant influenza A(H1N1)pdm09 virus carrying the H275Y neuraminidase (NA) mutation. To determine the frequency and the extent of this viral variant spread in the nearest major city to Newcastle, we performed a sequence-based genotypic assessment on samples from 143 oseltamivir untreated and 23 oseltamivir post-treatment individuals with influenza collected contemporaneously in Sydney, 120 km southwest of Newcastle. The detection of two of 143 (1.4%) community-derived samples containing H275Y suggests a low prevalence of oseltamivir-resistant influenza A(H1N1)pdm09 virus in the general community and no convincing evidence of spread of the NA H275Y-bearing influenza A(H1N1)pdm09 virus. In oseltamivir treated patients, oseltamivir-resistant influenza A(H1N1)pdm09 virus continue to emerge with three of 23 (13%) post-treatment samples containing the H275Y mutation. The observation of signature mutations and distinct phylogenetic relationship in full-length sequences of haemagglutinin and neuraminidase genes derived from 2011 strains against 2009 strains indicates continued genetic evolution and antigenic drift of the influenza A(H1N1)pdm09 viruses circulating in Australia.

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Characterization of influenza A(H1N1)pdm09 viruses in Germany in season 2019-2020 – co-circulation of an antigenic drift variant

10.22541/au.162908014.49850019/v1 ◽

2021 ◽

Author(s):

Marianne Wedde ◽

Djin-Ye Oh ◽

Silke Buda ◽

Andrea Thürmer ◽

Sandra Kaiser ◽

...

Keyword(s):

Influenza A ◽

Influenza Season ◽

Vaccine Virus ◽

Influenza Viruses ◽

Antigenic Drift ◽

Neuraminidase Inhibitors ◽

Pdm09 Virus ◽

Time Period ◽

Influenza A H1n1

Background Influenza A(H1N1)pdm09 virus entered the human population in 2009 and evolved within this population for more than ten years. Despite genetic evolution no remarkable changes in the antigenic reactive pattern of these viruses were observed so far. Methods Primary respiratory samples of the German influenza virological sentinel were investigated by qPCR. Influenza virus-positive samples were characterized genetically and antigenetically. Results In December 2019, a antigenic drift variant characterized by an N156K substitution in the hemagglutinin of influenza A(H1N1)pdm09 virus emerged in Germany, which exhibited a reactivity to ferret antiserum that was an average 6 log2 lower than the vaccine virus A/Brisbane/02/2018 and the other A(H1N1)pdm09 viruses circulating in the influenza season 2019-2020. These viruses accounted for 20% of all A(H1N1)pdm09 viruses characterized in the German influenza sentinel. Patients infected with these viruses had a shorter median time period of medical consultation after onset of symptoms and were more frequently treated with neuraminidase inhibitors in comparison to patients infected with other A(H1N1)pdm09 viruses. Conclusions This parallel circulation of two antigenic variants of A(H1N1)pdm09 viruses which differ remarkably in their antigenic reactive pattern contributes to a greater variability in circulating influenza viruses and challenges vaccination.

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Seroprevalence study of infection with influenza A(H1N1)pdm09 virus in San Felipe Town, Chile

World Journal of Cardiovascular Diseases ◽

10.4236/wjcd.2013.37075 ◽

2013 ◽

Vol 03 (07) ◽

pp. 476-482

Author(s):

Olea Andrea ◽

Fasce Rodrigo ◽

Aguilera Ximena ◽

Oliva Otavio ◽

Muñoz Sergio ◽

...

Keyword(s):

Influenza A ◽

Seroprevalence Study ◽

Pdm09 Virus ◽

Influenza A H1n1

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Fluctuations in influenza-like illness epidemics and suicide mortality: A time-series regression of 13-year mortality data in South Korea

PLoS ONE ◽

10.1371/journal.pone.0244596 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0244596

Author(s):

Sun Jae Jung ◽

Sung-Shil Lim ◽

Jin-Ha Yoon

Keyword(s):

Time Series ◽

South Korea ◽

Influenza A ◽

Suicide Mortality ◽

Mortality Data ◽

Time Series Regression ◽

Influenza Like Illness ◽

Pdm09 Virus ◽

Influenza A H1n1 ◽

Novel Influenza A

Aims We explored the association between influenza epidemic and suicide mortality rates in a large population using a time-series regression of 13-year mortality data in South Korea. Methods Weekly suicide mortalities and influenza-like illness (ILI) were analyzed using time series regression. Regression coefficient for suicide mortality based on percentage change of ILI was calculated using a quasi-Poisson regression. Non-linear distributed lag models with quadratic function up to 24 weeks were constructed. Results The association between ILI and suicide mortality increased significantly up to 8 weeks post-influenza diagnosis. A significant positive association between ILI and suicide mortality was observed from 2009, when a novel influenza A(H1N1)pdm09 virus provoked a worldwide pandemic. No meaningful association between these factors was observed before 2009. Conclusion There was a significant positive relationship between ILI and suicide mortality after 2009, when a novel influenza A(H1N1)pdm09 virus provoked a worldwide pandemic.

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