FIG. 5.

Binding of CEA N domain to gonococci expressing chimeric Opa proteins. Bacteria were incubated in HEPES buffer containing His₆-tagged CEA N domain (8) for 20 min at 37°C, spun, and washed. Cell pellets were boiled, separated by SDS-PAGE, blotted onto nitrocellulose, and probed with a mouse monoclonal anti-His₆ antibody, followed by protein A-HRP. Detection was with the ECL kit from Amersham. Numbers on the left are molecular masses in kilodaltons.