In vivo and in vitro expression of outer membrane components of Haemophilus influenzae.

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.