FIG 3 .

Bacterial lipopolysaccharide binds to and reduces the stability of influenza A virus. (A) Stability of a human H1N1 WSN-GFP virus and an avian H3N8 virus after incubation for 1 h at various temperatures with lipopolysaccharide (LPS) (n = 3). (B) Output titers of H1N1 WSN-GFP and H3N8, across a range of input titers, from tissue culture cells either (i) pretreated with LPS or water control and then infected or (ii) infected immediately after mixing the viruses with LPS or water (n = 4). BDL, below detectable limit. (C) Binding of biotinylated LPS to H1N1 PR8 after incubation for 1 h at 37°C (n = 2). (D) Long-term persistence of a human H1N1 PR8 and avian H3N8 in water (n = 13 or 12), or water containing diluted LPS (n = 6 or 7) at 25°C. The horizontal dotted line represents the limit of detection. (E) Aquatic freeze-thaw stability of a human H1N1 PR8 and avian H3N8 in LPS or water control (n = 4). Data are represented either as the data for individual replicates or as the means plus SEM. Statistical significance was assessed using a Student’s t test (A and E) or an F test on the linear regressions (B and D) and indicated as follows: ***, P < 0.001; *, <0.05, n.s., nonsignificant.