Fig. 6

Impact of vaccine-induced antibodies on B. pertussis adhesion to A549 cells. a Schematic representation of the assay. b Sera from mice vaccinated with an acellular pertussis vaccine (aP) and a whole cell pertussis vaccine (wP) (8 mice/group) were pooled, serially diluted in infection medium and incubated with labeled wild-type B. pertussis Tohama I for 1 h. Pre-immune sera and sera from unvaccinated mice were used as negative control. A549 cells were then infected with the bacteria/sera mixtures for 1 h and, after extensive washes to remove unbound bacteria, cell-associated bacteria were quantified by fluorescence reading at Ex/Em 485/535 nm. Results represent mean ± SD from there independent experiments each performed in triplicates. c Sera from individual mice vaccinated with aP and wP vaccines (8 mice/group) were diluted 1 to 80 and adhesion assay was performed as described in B. Sera from unvaccinated individual mice were used as negative control. Results represent mean ± SD from a single experiment performed in triplicates; ****P < 0.0001, **P < 0.01