Characterization of pili expressed by Haemophilus ducreyi

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Haemophilus ducreyi is the causative agent of chancroid, a sexually transmitted infection.
• Pili, filamentous appendages on bacterial surfaces, are often involved in adhesion and virulence.
• The presence and characteristics of H. ducreyi pili have not been extensively studied.

Purpose of the Study:

• To investigate the presence and characteristics of pili in Haemophilus ducreyi strains.
• To determine the molecular weight of the pilin monomer.
• To assess the stability of pilus expression and potential erythrocyte binding.

Main Methods:

• Transmission electron microscopy (TEM) was used to visualize pili on bacterial cells.
• Pilin extracts were prepared and analyzed using SDS-PAGE.
• Pilus stability was assessed through serial passage on agar plates.
• Erythrocyte binding assays were performed with bacterial colonies.

Main Results:

• Piliated cells were identified in 10 out of 12 H. ducreyi strains examined by TEM.
• Pili were confirmed in extracts from all 12 H. ducreyi strains.
• SDS-PAGE revealed a predominant protein of 24 kDa in pilin extracts, identified as the pilin monomer.
• Pilus expression remained stable after 52 passages on agar.
• No evidence of erythrocyte binding to H. ducreyi colonies was observed.

Conclusions:

• Haemophilus ducreyi expresses pili, with a pilin monomer molecular mass of 24 kDa.
• Pilus expression is stable and not readily lost during laboratory cultivation.
• H. ducreyi pili may not interact with erythrocyte receptors, suggesting alternative adhesion mechanisms.