Figure 6. Influence of the Y. enterocolitica O:3 O-antigen on host cell invasion.
Y. enterocolitica wildtype strains YeO3 and 8081v, and outer core and/or O-antigen deficient derivatives (YeO3-OC, YeO3-R2, YeO3-OCR) were grown at 25°C and 37°C. (A) About 5×104 HEp-2 cells were infected with 5×105 bacteria. After centrifugation of the bacteria onto the monolayer, cell association (adhesion+invasion) was monitored and internalization efficiency of the bacteria was determined by the gentamicin protection assay. E. coli K-12 was used as negative control. Data are presented as means ± standard deviations of three independent experiments performed in duplicate. Data were analyzed by the students t test. Stars indicate the results that differed significantly from those of YeO3 with * (P<0.05), ** (P<0.01), and *** (P<0.001) (B) Whole cell extracts were prepared from overnight cultures, separated on SDS-polyacrylamide gels and analyzed by western blotting using polyclonal antibodies directed against InvA and YadA. As a molecular marker the PageRuler Prestained Protein Ladder was loaded on the left.