OUTER-MEMBRANE PROTEIN-CD OF BRANHAMELLA-CATARRHALIS - SEQUENCE CONSERVATION IN STRAINS RECOVERED FROM THE HUMAN RESPIRATORY-TRACT

Branhamella catarrhalis causes lower respiratory tract infections in p atients with chronic obstructive pulmonary disease. The outer membrane protein CD (OMP-CD) of B. catarrhalis is a major, heat-modifiable OMP . The goals of this study are to characterize the degree of conservati on of OMP-CD among strains and to investigate if OMP-CD maintains its homogeneity under the effect of host immune selective pressure. Isolat es of B. catarrhalis were collected prospectively from patients with b ronchiectasis and chronic bronchitis. We studied the OMP-CD gene by an alysis of PCR restriction fragment length polymorphisms (PCR-RFLP) and further determined DNA sequence of the CD gene of eight selected isol ates. Five patterns of PCR-RFLP of the OMP-CD gene were observed among all isolates when the gene was digested with Sau3Al. The sequence ana lysis revealed a high degree of homogeneity in OMP-CD among strains of B. catarrhalis. Three regions of OMP-CD with minimal sequence heterog eneity were identified. The sequences of the OMP-CD gene of isolates c ollected from patients colonized with the same strain for up to 6 mont hs was identical. These observations establish that the OMP-CD of B. c atarrhalis recovered from clinical isolates is highly conserved among strains. (C) 1995 Academic Press Limited