Characterization of Cell Proteins of Haemophilus ducreyi by Polyacrylamide Gel Electrophoresis

Abstract
The whole-cell proteins of 105 clinical isolates of Haemophilus ducreyi from several geographic sources (North America, Africa, Asia, and Europe) were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein profiles were reproducible and unaffected by repeated subculturing or age of culture. At least seven different subtypes were determined by proteins in the molecular weight range of 24,000–50,000. These proteins are located in the outer membrane of the cell, as determined by SDS-PAGE of the sarcosinate-insoluble membrane preparations of these strains. Thirteen isolates from a Winnipeg, Manitoba, Canada, outbreak of chancroid had identical patterns, suggesting a common origin. Although H ducreyi shares a number of proteins in common with other Haemophilus species, the protein profiles appear to be species specific. Heterogeneity in the protein composition of H ducreyi has provided a basis for subtyping, which could be of value in future epidemiologic studies.