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Expression of OmpP2A and OmpP2B is not required for pustule formation by Haemophilus ducreyi in human volunteers
Diane Janowicz1, Nicole R Luke, Kate R Fortney
1Department of Medicine, School of Medicine, Indiana University, Indianapolis, IN 46202, USA.
Abstract:
Haemophilus ducreyi express two porin proteins, termed OmpP2A and OmpP2B. To test whether expression of OmpP2A and OmpP2B was necessary for virulence in humans, eight volunteers were experimentally infected with the parent (35000HP) in one arm and a double OmpP2A OmpP2B mutant (35000HP::P2AB) in the other arm. The pustule formation rates were 58.3% (95% CI, 33.2-83.5%) for the parent and 41.7% (95% CI, 19.3-64.0%) for the mutant (P=0.25). Biopsy of 35000HP and 35000HP::P2AB-infected sites yielded similar amounts of bacteria in quantitative culture. These results indicate that expression of OmpP2A and OmpP2B is not necessary to initiate disease or to progress to pustule formation in humans.
Insights
The expression of OmpP2A and OmpP2B porin proteins by Haemophilus ducreyi is not essential for initiating human infection or causing pustule formation. Bacterial loads were similar between the parent strain and the double mutant.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Haemophilus ducreyi causes chancroid, a sexually transmitted infection.
- Porin proteins, such as OmpP2A and OmpP2B, are surface-exposed and may play roles in bacterial virulence.
- Understanding the role of specific bacterial components in disease is crucial for developing targeted interventions.
Purpose of the Study:
- To investigate the necessity of OmpP2A and OmpP2B porin protein expression for Haemophilus ducreyi virulence in human infection.
- To determine if these porins are required for the initiation of disease and pustule development.
Main Methods:
- Experimental human infection model using eight volunteers.
- Infection with the parent Haemophilus ducreyi strain (35000HP) and a double OmpP2A OmpP2B mutant (35000HP::P2AB) in separate arms.
- Assessment of pustule formation rates and quantitative bacterial culture from biopsy samples.
Main Results:
- Pustule formation rates were 58.3% for the parent strain and 41.7% for the double mutant, with no statistically significant difference (P=0.25).
- Quantitative cultures from infected sites revealed similar bacterial loads for both the parent and mutant strains.
- The absence of OmpP2A and OmpP2B did not impede bacterial colonization or disease progression.
Conclusions:
- The expression of OmpP2A and OmpP2B porin proteins is not essential for Haemophilus ducreyi to initiate infection in humans.
- These porins are not necessary for the development of pustules or for maintaining bacterial loads during infection.
- Virulence of Haemophilus ducreyi in human skin infection may not depend on OmpP2A and OmpP2B.
