Known meningococcal invasins do not contribute to CEACAM1-mediated internalization of non-opaque meningococci.

<p>(<b>A</b>) 293 cells were transfected with pcDNA CEACAM1-4L-HA or with the empty control vector (pcDNA). Two days after transfection, cells were infected for 2 h with <i>E. coli</i> strains recombinantly expressing NadA, Opc, or the parent strain. The number of internalised bacteria was determined by gentamicin protection assays. Results represent mean ± standard deviation of three independent experiments done in triplicate and show the percentage of recovered bacteria compared to CEACAM1. (<b>B</b>) Cells as in (A) were infected with Opa_CEA-expressing gonococci (Ngo Opa_CEA) and the number of internalised bacteria was determined as in (A). (<b>C</b>) Expression of recombinant NadA and Opc in <i>E. coli</i>. Expression of Opc was analysed in bacterial lysates by Western Blot using monoclonal anti-Opc antibody. Expression of recombinant NadA in <i>E. coli</i> was analysed by SDS-PAGE after induction with IPTG. The multimeric, functional form of NadA is indicated (arrow). As a negative control, non-induced <i>E. coli</i> or <i>E. coli</i> not transformed with recombinant proteins were used.