Figure 4.
Cell-binding assay to show binding of factor H (A) and VCP (B) to A549 cells challenged with H1N1 and H3N2. A549 cells (1 × 105 cells/ml) were seeded in a 96-well microtiter plate and incubated at 37°C overnight. Decreasing concentrations of factor H and VCP (10, 5, 2.5, and 1.25 μg), pre-incubated with IAV subtypes, were added to the corresponding wells, and incubated at room temperature for 1 h. After removing unbound protein and viral particles, the wells were fixed with 4% v/v paraformaldehyde, and probed with monoclonal anti-influenza virus H1 or polyclonal anti-influenza virus H3 antibodies. BSA was used as a negative control protein. Three independent experiments were carried out in triplicates and error bars expressed as ± SEM.