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Infection and Immunity, November 2004, p. 6271-6278, Vol. 72, No. 11
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.11.6271-6278.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Differential Expression of Porins OmpP2A and OmpP2B of Haemophilus ducreyi

Department of Microbiology and Immunology,¹ Witebsky Center for Microbial Pathogenesis and Immunology,² Department of Medicine, Division of Infectious Diseases, State University of New York at Buffalo, Buffalo, New York,⁴ Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada³

Received 18 June 2004/ Returned for modification 6 August 2004/ Accepted 11 August 2004

Haemophilus ducreyi is a strict human pathogen and the causative agent of the sexually transmitted disease chancroid. The genome of the human-passaged strain of H. ducreyi (35000HP) contains two homologous genes whose protein products have estimated molecular masses of 46 and 43 kDa. A comparative analysis of the deduced amino acid sequences revealed that these proteins share 27 to 33% identity to the outer membrane protein P2 (OmpP2), a major porin of Haemophilus influenzae. Therefore, these proteins have been designated OmpP2A and OmpP2B, respectively. The detection of ompP2A and ompP2B transcripts by reverse transcriptase PCR indicated that these genes were independently transcribed in H. ducreyi 35000HP. Western blot analysis of outer membrane proteins isolated from a geographically diverse collection of H. ducreyi clinical isolates revealed that OmpP2A and OmpP2B were differentially expressed among these strains. Although PCR analysis suggested that ompP2A and ompP2B were conserved among the strains tested, the differential expression observed was due to nucleotide additions and partial gene deletions. Purified OmpP2A and OmpP2B were isolated under nondenaturing conditions, and subsequent analysis demonstrated that these two proteins exhibited porin activity. OmpP2A and OmpP2B are the first porins described for H. ducreyi.

Editor: D. L. Burns