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Porphyrin ring source can alter the outer membrane protein profile of non-typable Haemophilus influenzae
I MacIver1, T O'Reilly, M R Brown
1Pharmaceutical Sciences Institute, Aston University, Birmingham.
Abstract:
Porphyrin ring source appears to alter the outer membrane protein (OMP) profile of some, but not all, non-typable (NT) Haemophilus influenzae strains isolated from sputum. When haemin was replaced with protoporphyrin IX, 41% of strains examined produced increased amounts of a polypeptide of 84 Kda and new OMPs of either 120 or 150 Kda. Immunoblotting with paired patient's sera revealed that antibodies reactive with these proteins were present, demonstrating OMP antigenicity and expression in vivo and indicating that these isolates of NT H. influenzae may display an altered OMP phenotype when growing in the human lung.
Insights
The source of the porphyrin ring affects outer membrane protein (OMP) expression in some non-typable Haemophilus influenzae (NT H. influenzae). This change in OMP profile was observed in vitro and suggests potential in vivo alterations in the human lung.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- Non-typable Haemophilus influenzae (NT H. influenzae) are significant respiratory pathogens.
- Outer membrane proteins (OMPs) play crucial roles in bacterial adaptation and host interaction.
- The influence of nutrient availability, specifically porphyrin sources, on NT H. influenzae OMP expression is not fully understood.
Purpose of the Study:
- To investigate the impact of different porphyrin ring sources on the OMP profile of NT H. influenzae.
- To determine if changes in OMP expression occur in vivo.
Main Methods:
- Culturing of NT H. influenzae strains with varying porphyrin sources (haemin vs. protoporphyrin IX).
- Analysis of bacterial protein profiles using SDS-PAGE.
- Immunoblotting assays using patient sera to detect antibody responses to OMPs.
Main Results:
- Replacement of haemin with protoporphyrin IX induced changes in OMP profiles in 41% of tested NT H. influenzae strains.
- Increased production of an 84 Kda polypeptide and novel OMPs (120 or 150 Kda) were observed.
- Patient sera showed reactivity against these altered OMPs, confirming their antigenicity and expression in vivo.
Conclusions:
- The porphyrin source can significantly alter the OMP phenotype of NT H. influenzae.
- These alterations are immunogenic and suggest that NT H. influenzae can adapt its OMP expression in the human lung environment.
- Understanding these adaptive mechanisms is crucial for developing targeted therapies against NT H. influenzae infections.