FIG. 3.

Reactivity of convalescent-phase sera to recombinant Tf and Lf receptors. The regions encoding the mature forms of the individual Tf and Lf receptor proteins were PCR amplified and ligated in frame with the malE gene of the pMal-c2 vector for production of Mbp fusion proteins. Expression of the Mbp fusions was induced by the addition of IPTG, and the cells were boiled in Laemmli sample buffer prior to SDS-PAGE (7% gel). The electroblotted proteins were either stained for protein (lanes 1 to 4) or probed with convalescent-phase antiserum (1:500) from the patient with a pulmonary infection attributed to M. catarrhalis N141. Lanes 1 and 5, Mbp::TbpA (strain 4223 tbpA gene); lanes 2 and 6, Mbp::TbpB (strain 4223 tbpB gene); lanes 3 and 7, Mbp::LbpA (strain N141 lbpA gene); lanes 4 and 8, Mbp::LbpB (strain N141 lbpB gene). Symbols are as in Fig. 1 and 2.