14 research outputs found

    Performances of the 6 kits evaluated in this study for a panel of 9 viruses or groups of viruses with reference to the combination of duplex PCR tests (Argene/bioMérieux) used as gold standard.

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    a<p>Kit having no probe for the detection of HKU1 coronavirus.</p>b<p>Kit having a probe for detecting 229E coronavirus only.</p>c<p>All the tested kits did not detect all the coronavirus types (see notes <sup>a</sup> and <sup>b</sup>).</p

    List of pathogens that were considered to be present in the panel of the 88 specimens according the combination of duplex PCR tests (Argene/bioMérieux) used as gold standard.

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    a<p>type 1 (n = 2), type 3 (n = 3) and type 4 (n = 5).</p>b<p>type NL63 (n = 6), type OC43 (n = 8), type 229E (n = 1), type HKU1 (n = 6) and untyped (n = 4).</p

    Functional Balance between the Hemagglutinin and Neuraminidase of Influenza A(H1N1)pdm09 HA D222 Variants

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    <div><p>D222G/N substitutions in A(H1N1)pdm09 hemagglutinin may be associated with increased binding of viruses causing low respiratory tract infections and human pathogenesis. We assessed the impact of such substitutions on the balance between hemagglutinin binding and neuraminidase cleavage, viral growth and <i>in vivo</i> virulence.Seven viruses with differing polymorphisms at codon 222 (2 with D, 3 G, 1 N and 1 E) were isolated from patients and characterized with regards hemagglutinin binding affinity (Kd) to α-2,6 sialic acid (SAα-2,6) and SAα-2,3 and neuraminidase enzymatic properties (Km, Ki and Vmax). The hemagglutination assay was used to quantitatively assess the balance between hemagglutinin binding and neuraminidase cleavage. Viral growth properties were compared <i>in vitro</i> in MDCK-SIAT1 cells and <i>in vivo</i> in BALB/c mice. Compared with D222 variants, the binding affinity of G222 variants was greater for SAα-2,3 and lower for SAα-2,6, whereas that of both E222 and N222 variants was greater for both SAα-2,3 and SAα-2,6. Mean neuraminidase activity of D222 variants (16.0 nmol/h/10<sup>6</sup>) was higher than that of G222 (1.7 nmol/h/10<sup>6</sup> viruses) and E/N222 variants (4.4 nmol/h/10<sup>6</sup> viruses). The hemagglutination assay demonstrated a deviation from functional balance by E222 and N222 variants that displayed strong hemagglutinin binding but weak neuraminidase activity. This deviation impaired viral growth in MDCK-SIAT1 cells but not infectivity in mice. All strains but one exhibited low infectious dose in mice (MID50) and replicated to high titers in the lung; this D222 strain exhibited a ten-fold higher MID50 and replicated to low titers. Hemagglutinin-neuraminidase balance status had a greater impact on viral replication than hemagglutinin affinity strength, at least <i>in vitro</i>, thus emphasizing the importance of an optimal balance for influenza virus fitness. The mouse model is effective in assessing binding to SAα-2,3 but cannot differentiate SAα-2,3- from SAα-2,6- preference, nor estimate the hemagglutinin-neuraminidase balance in A(H1N1)pdm09 strains.</p></div

    Quantitative assessment of HA binding and the associated NA activity of H1N1pdm HA 222 variants.

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    <p>Initial HA titers were measured using guinea pig red blood cells after 75 min incubation at 4°C and final HA titers were determined after 120 min incubation at 37°C as described in Methods. The end point NA activity was measured on 16 UHA viruses diluted ten-fold and incubated with MU-NANA at 37°C for 1 hr.</p
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