Identification and characterization of a serotype b-specific segment of the Haemophilus influenzae genome.

Within the region of the Haemophilus influenzae serotype b genome required for capsule expression, a 4.6-kilobase segment was cloned, used as a hybridization probe, and found to be specific for serotype b strains. Deletion mutagenesis within this segment defined a locus necessary for serotype b capsule production and another involved in maintenance of wild-type colony appearance.