Molecular biology of Chlamydia pneumoniae surface proteins and their role in immunopathogenicity.
BACKGROUND
The association of Chlamydia pneumoniae with the development of atherosclerosis is based on serology and on detection of C pneumoniae-specific DNA by polymerase chain reaction in the atheromas.


RESULTS
Because the humoral immune response frequently recognizes epitopes present on the surface of the bacteria, we analyzed what components are present on the C pneumoniae surface. We identified a family of proteins, the GGAI or Omp4-15 proteins, of which at least 3 are present on the surface of C pneumoniae. We immunized rabbits with recombinant GGAI proteins and used these antibodies in immunofluorescence microscopy of experimentally infected mice. In lung sections, a massive infiltration with polymorph nuclear neutrophil cells was observed. In the bronchial epithelial cells, C pneumoniae inclusions were seen. Evidence was found of differential expression of the GGAI proteins.


CONCLUSIONS
On the basis of surface localization, differential expression, and the fact that the proteins are recognized by the human humoral immune response, we speculate whether these proteins, in addition to the lipopolysaccharides, are of importance for the immunopathogenesis of C pneumoniae.
Christiansen
G
G
Department of Medical Microbiology, Department of Molecular and Structural Biology, University of Aarhus, Denmark.
Boesen
T
T
Hjerno
K
K
Daugaard
L
L
Mygind
P
P
Madsen
A S
AS
Knudsen
K
K
Falk
E
E
Birkelund
S
S
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D016993:Chlamydophila pneumoniae / Q000378:metabolism* / Q000472:pathogenicity*; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D016253:Microscopy, Immunoelectron; D008970:Molecular Weight; D011487:Protein Conformation; D012698:Serologic Tests; D014774:Virulence
D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides