Fig. 1
Analysis of optimum MOI of Ab to human respiratory epithelial cells. Control: 0.45% NaCl. a Microscopy observations of the effect of Ab on epithelial cells (2 × 105 cells per well) at different MOIs (co-cultured for 4 h). Scale bar = 30 μm. Red arrows: bubble-like (denucleated) dead cells with bacterial adhesion visible around (especially in the MOI 50 and MOI 100 experimental groups); Yellow arrows: the phenomenon of bacterial aggregation. b The qPCR results indicating Ab invasion of epithelial cells (including strong adhesion) at different MOIs (host cells and bacteria were co-cultured for 4 h and 1 × 105 cells were isolated). The differences in the Ct values (MOI 100 group < MOI 50 group < MOI 10 group < MOI 1 group) among all the groups were statistically significant, as determined by the SNK test (P < 0.05). The differences between the MOI 1 and MOI 10 groups and the MOI 10 and MOI 50 groups were greater than between the MOI 50 and MOI 100 groups. The higher the MOI was, the greater the Ab invasion of epithelial cells. c Ab infection TCRPs of epithelial cells (20,000 cells per well) at different MOIs. t: point at which bacteria or NaCl were added (after background readings for the E-Plate were obtained and the plate was incubated at room temperature for 30 min). The “double peak” phenomenon emerged during Ab infection. The smaller the MOI was, the later and higher the peak CI was, the more significant the phenomenon was. Representative curves are an average of three replicate wells