Porphyrin ring source can alter the outer membrane protein profile of non-typable Haemophilus influenzae.

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.