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Incidence of H1N1 2009 virus infection through the analysis of paired plasma specimens among blood donors, France.

ABSTRACT: BACKGROUND: Knowledge of the age-specific prevalence of seroprotection and incidence of seroconversion infection is necessary to complement clinical surveillance data and statistical models. It provides the basis for estimating the future impact of influenza A (H1N1pdm09) and implementing appropriate prevention and response strategies. METHODS: Using a cross-sectional design, two-stage stratified sampling and paired plasma samples, we estimated the age-specific prevalence of a protective level of H1N1pdm09 antibodies in the French adult population before and after the 2009/10 pandemic, and the proportion of those susceptible that seroconverted due to infection, from a single sample of 1,936 blood donors aged 20-70 years in mainland France in June 2010. Samples with a haemagglutination inhibition (HI) titre ?1?40 were considered seropositive, and seroconversion due to infection was defined as a 4-fold increase in titre in the absence of H1N1pdm09 vaccination or pre-pandemic seropositivity. RESULTS: Out of the 1,936 donors, 1,708 were included in the analysis. Seroprevalence before the pandemic was 6.7% (95% CI 5.0, 8.9) with no significant differences by age-group (p?=?0.3). Seroprevalence afterwards was 23.0% (95% CI 17.7, 29.3) with 20-29 year olds having a higher level than older groups (p<0.001). Seroconversion due to infection was 12.2% (95% CI 6.9, 20.5). Younger age-group, vaccination against H1N1 and being seropositive before the pandemic were strongly associated with post-pandemic seropositivity. CONCLUSIONS: Before the 2009/2010 winter influenza season, only 6.7% of the French mainland population aged 20-70 had a level of antibodies usually considered protective. During the first pandemic wave, 12.2% of the population seroconverted due to infection and the seroprevalence after the wave rose to 23%, either due to prepandemic seropositivity, infection or vaccination. This relatively low latter figure contributed to an extension of target groups for influenza vaccination for the 2010/2011 season.

SUBMITTER: Bone A

PROVIDER: S-EPMC3310844 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Incidence of H1N1 2009 virus infection through the analysis of paired plasma specimens among blood donors, France.

Bone Angie A Guthmann Jean-Paul JP Assal Azzedine A Rousset Dominique D Degeorges Armelle A Morel Pascal P Valette Martine M Enouf Vincent V Jacquot Eric E Pelletier Bertrand B Le Strat Yann Y Pillonel Josiane J Fonteneau Laure L van der Werf Sylvie S Lina Bruno B Tiberghien Pierre P Lévy-Bruhl Daniel D

PloS one 20120322 3

<h4>Background</h4>Knowledge of the age-specific prevalence of seroprotection and incidence of seroconversion infection is necessary to complement clinical surveillance data and statistical models. It provides the basis for estimating the future impact of influenza A (H1N1pdm09) and implementing appropriate prevention and response strategies.<h4>Methods</h4>Using a cross-sectional design, two-stage stratified sampling and paired plasma samples, we estimated the age-specific prevalence of a prote ...[more]

PMID: 22457734

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Project description:A/H1N1 2009 pandemic influenza virus (A/H1N1/pdm09) was first identified as a novel pandemic influenza A virus (IAV) in 2009. Previously, we reported that many viral antigens were detected in type II alveolar epithelial cells (AEC-IIs) within autopsied lung tissue from a patient with A/H1N1/pdm09 pneumonia. It is important to identify the association between the virus and host cells to elucidate the pathogenesis of IAV pneumonia. To investigate the distribution of virus particles and morphological changes in host cells, the autopsied lung specimens from this patient were examined using transmission electron microscopy (TEM) and a novel scanning electron microscopy (SEM) method. We focused on AEC-IIs as viral antigen-positive cells and on monocytes/macrophages (Ms/Mϕs) and neutrophils (Neus) as innate immune cells. We identified virus particles and intranuclear dense tubules, which are associated with matrix 1 (M1) proteins from IAV. Large-scale two-dimensional observation was enabled by digitally "stitching" together contiguous SEM images. A single whole-cell analysis using a serial section array (SSA)-SEM identified virus particles in vesicles within the cytoplasm and/or around the surfaces of AEC-IIs, Ms/Mϕs, and Neus; however, intranuclear dense tubules were found only in AEC-IIs. Computer-assisted processing of SSA-SEM images from each cell type enabled three-dimensional (3D) modeling of the distribution of virus particles within an ACE-II, a M/Mϕ, and a Neu.IMPORTANCE Generally, it is difficult to observe IAV particles in postmortem samples from patients with seasonal influenza. In fact, only a few viral antigens are detected in bronchial epithelial cells from autopsied lung sections. Previously, we detected many viral antigens in AEC-IIs from the lung. This was because the majority of A/H1N1/pdm09 in the lung tissue harbored an aspartic acid-to-glycine substitution at position 222 (D222G) of the hemagglutinin protein. A/H1N1/pdm09 harboring the D222G substitution has a receptor-binding preference for α-2,3-linked sialic acids expressed on human AECs and infects them in the same way as H5N1 and H7N9 avian IAVs. Here, we report the first successful observation of virus particles, not only in AEC-IIs, but also in Ms/Mϕs and Neus, using electron microscopy. The finding of a M/Mϕ harboring numerous virus particles within vesicles and at the cell surface suggests that Ms/Mϕs are involved in the pathogenesis of IAV primary pneumonia.

Dataset Information

Incidence of H1N1 2009 virus infection through the analysis of paired plasma specimens among blood donors, France.

Publications

Incidence of H1N1 2009 virus infection through the analysis of paired plasma specimens among blood donors, France.

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