Figure 5.

Neuraminidases increase pneumococcal interaction with human lung cells. (A) A549 cells infected with S. pneumoniae D39 and corresponding isogenic neuraminidase gene deletion mutants (left panel), or D39 wild-type in presence of α-neuraminidase mAbs (2 μM each) or 4 μM control IgG1 (middle panel). A549 cells treated with recombinant neuraminidases (1 nM each) or control protein (3 nM) and infected with D39ΔnanAΔnanB, or D39 wild-type and control protein (right panel). B: A549 cells infected with EF3030 or Sp#5 strains in the presence of α-neuraminidase mAbs (2 µM each) or control IgG1 (4 µM). C: Primary human lung tissues infected with S. pneumoniae EF3030 or Sp#5 in the presence of α-Ply (2 µM) + α-neuraminidase mAbs (2 µM each) or α-Ply (2 µM) + control IgG1 (4 µM). CFUs recovered from infected cells were calculated relative to those obtained with comparator strains or treatments indicated on the y-axes. Results from two independent experiments with at least biological triplicates are depicted as mean with standard deviation.