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In vivo and in vitro expression of outer membrane components of Haemophilus influenzae
L van Alphen1, L Geelen-van den Broek, M van Ham
1Department of Medical Microbiology, University of Amsterdam, The Netherlands.
Abstract:
The outer membrane protein composition of Haemophilus influenzae grown under a variety of culture conditions including growth in sputum and serum, and intraperitoneally in rats was analyzed. The pattern of the major outer membrane proteins, a, b,c, d, e and P6 remained very similar under all these conditions. Outer membrane proteins expressed during iron limitation were also expressed in bacteria growing in rats, in serum or in sputum. To determine the expression of the major outer membrane proteins and lipopolysaccharide in patient materials (sputum, cerebrospinal fluid, postmortem tissue) monoclonal antibodies specific for the outer membrane proteins a, b,c, d and P6 as well as lipopolysaccharide were used in immunoblotting. They showed the same reaction patterns with bacteria in the patient materials as with the bacteria isolated from these specimens. We conclude that the major outer membrane components expressed under in vitro conditions are also expressed in various clinical materials during infection.
Insights
Haemophilus influenzae outer membrane protein expression is consistent across various conditions, including in vivo and in vitro environments. These key outer membrane proteins are also present in clinical samples during infection.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- The outer membrane of Haemophilus influenzae is crucial for its interaction with the host.
- Understanding the expression of outer membrane proteins is vital for developing effective treatments and vaccines.
Purpose of the Study:
- To analyze the outer membrane protein composition of Haemophilus influenzae under diverse growth conditions.
- To compare protein expression in vitro with that observed in clinical specimens.
Main Methods:
- Haemophilus influenzae was cultured under various conditions (sputum, serum, rat models).
- Outer membrane proteins were analyzed using immunoblotting with monoclonal antibodies.
- Expression in patient materials (sputum, CSF, tissue) was assessed.
Main Results:
- Major outer membrane protein profiles (proteins a, b, c, d, e, P6) remained consistent across different culture conditions.
- Iron-limited outer membrane proteins were also expressed in vivo (rats, serum, sputum).
- Monoclonal antibody reactions in patient materials mirrored those of isolated bacteria.
Conclusions:
- The major outer membrane components of Haemophilus influenzae are conserved regardless of in vitro or in vivo growth conditions.
- In vitro findings accurately reflect in vivo expression patterns.
- These conserved outer membrane proteins are relevant during active H. influenzae infections.