FIG. 8.

Introduction of the lptA gene on a multicopy plasmid into wild-type N. meningitidis does not enhance LOS modification with the PEA group or bacterial adhesion to HBMEC. (A) Adhesion of HT1125 harboring a plasmid containing the lptA gene (pHT435) or a vector plasmid (pHT261) to HBMEC. The bacterial adhesion was examined at MOIs of 5,000, 500, 50, and 5. Mean CFU of adherent bacteria per monolayer of HBMEC in at least three experiments are shown, and error bars represent the standard errors of the means. (B) Western blotting for LptA protein. Bacterial extracts equivalent to an OD₆₀₀ of 0.05 were analyzed by Western blotting. Lane 1, HT1125 (ST-2032 wild type); lane 2, HT1222 (ST-2032 ΔlptA); lane 3, HT1125 harboring pHT261 (vector); lane 4, HT1125 harboring pHT435 (lptA⁺ on a plasmid). (C) MALDI-TOF spectra of lipid A purified from HT1125 harboring pHT261 (upper panel) and from HT1125 harboring pHT435 (lower panel). The masses of the major fragments are indicated at the tops of the corresponding peaks. The fragments and peaks of these ions were nearly identical in the two N. meningitidis transformants.