FIG. 2.

M. catarrhalis contains only one gene encoding the MID protein. (A) PCR analysis demonstrating mid genes ranging from 6,000 to 7,000 bp. (B) Southern blot of SspI-digested genomic DNA. Our model strains Bc5, BBH17, Perez112, RH1, and RH4 were compared to five randomly selected clinical isolates. Genomic DNA from M. catarrhalis was prepared. PCR was run with a primer pair annealing to a sequence upstream of the ORF and a conserved area downstream including the stop codon sequence. In the Southern blot experiment, DNA was digested with SspI, which cleaves the mid gene once, and subjected to Southern blot analysis using a ³³P-labeled probe originating from the 3′ end of the gene.