Figure 7. Coexpression of invasin and YadA is necessary for efficient invasion at 37°C.
Y. enterocolitica strain O:8 strain 8081v, Y. enterocolitica O:3 strain Y1 and isogenic invA and yadA deficient mutant derivatives were grown overnight at 25°C and 37°C. (A) About 5·104 HEp-2 cells were infected with 5·105 bacteria and after centrifugation of the bacteria onto the monolayer the samples cell association (adhesion+invasion) was monitored and internalization efficiency of the bacteria was determined by the gentamicin protection assay. Data are presented as means ± standard deviations of three independent experiments performed in duplicate. Data were analyzed by the students t test. Data were analyzed by the students t test. Stars indicate the results that differed significantly from those of Y1 with * (P<0.05), ** (P<0.01), and *** (P<0.001). (B) Whole cell extracts were prepared from the 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.