Muscle cell death and lysis after infection by influenza A(H1N1).

<div><p><b>A</b>, <b>B</b>. The morphology of the actin cytoskeleton (red) of myotubes and myoblasts (donor CHQ) was observed by immunofluorescence at various time points after infection by the A/California/7/2009 or A/Paris/1149/2008 isolate and in non-infected cultures grown in parallel. The nucleoprotein NP (green) was used to discriminate between infected and non-infected cells, and DAPI was used to stain the nucleus. Bars: A, 100µm, B, 20µm.</p> <p><b>C</b>, <b>D</b>. The concentration of lactate dehydrogenase (LDH) released in the culture supernatants was measured by an enzymatic assay at various time points after infection by the A/California/7/2009 or the A/Paris/1149/2008 isolate. This concentration was normalized using untreated and chemically-permeabilized non-infected cultures to calculate a rate of LDH release reflecting the index of cell permeabilization. Results are expressed as the mean and SD of two independent experiments on CHQ cells.</p>