FIG 4.

B. burgdorferi mutant lacking Bgp expression is impaired in binding to epithelial and endothelial cell lines. ³⁵S-labeled B31 5A18 (WT), bgpmut, and bgpcomp strains were incubated with epithelial (HEK293 and Vero) and endothelial (EA.hy926) cell lines. The bgpmut strain showed statistically significant reduction in binding to HEK293 and EA.hy926 cells compared to the WT and bgpcomp strains. Binding of the mutant strain to Vero cells was slightly reduced (ns). Binding of the bgpcomp strain, in which Bgp expression is restored, was comparable to that in the WT strain. Wells containing no cells were included as a control for nonspecific binding to wells. After subtracting the mean background (four empty wells) binding levels, the adjusted counts for all treated wells were divided by the total bacterial input for the respective strain, and the percent binding was calculated. Each bar represents the mean ± SD for quadruplicate samples. Statistical significance (**, P < 0.01; ***, P < 0.001; ****, P < 0.0001) was determined by the Student t test for comparison of samples with unequal variances.