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Infect Immun, April 1998, p. 1370-1376, Vol. 66, No. 4
Division of Infectious Diseases,
Received 19 November 1997/Returned for modification 5 January
1998/Accepted 15 January 1998
Chlamydia pneumoniae is a respiratory pathogen that has
been associated with chronic inflammatory diseases such as asthma and
atherosclerosis. Recent isolation of C. pneumoniae from
human carotid and coronary atheromas provides additional support for a
role of this organism in atherogenesis. We characterized the coronary
strain C. pneumoniae A-03 by sequence analysis of the major
outer membrane protein gene (omp1). In addition, the in vitro activities of A-03 and three respiratory strains of C. pneumoniae (BAL-16, TW-183, and T-2634) were examined in infected
human umbilical vein endothelial cells (HUVEC) by analysis of the
production of interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and soluble intercellular cell adhesion molecule 1 (sICAM-1). Sequence analysis of omp1 of C. pneumoniae
A-03, compared to prototype strains TW-183 and AR-39, revealed five
nucleotide changes resulting in nonsynonymous codons. Of interest was a
nonconservative amino acid substitution (Ser to Pro) in position 61 of
variable segment 1. In vitro, the extent of MCP-1, IL-8, and sICAM-1
production was dependent on the C. pneumoniae strain
examined at low multiplicities of infection following 24 h of
incubation. Strain A-03 displayed the lowest stimulatory activity in
infected HUVEC, while T-2634 induced the highest levels of MCP-1, IL-8,
and sICAM-1 among all strains examined. Heat-inactivated C. pneumoniae failed to stimulate production of these proteins by
all strains tested. In contrast, only partial inhibition was observed
by UV-inactivated organisms. Results from this study demonstrate that
unlike prototype respiratory strains of C. pneumoniae, the
coronary strain A-03 displays divergence in the omp1 gene.
In addition, the stimulation of chemokines and adhesion molecules
involved in the recruitment of leukocytes to sites of inflammation by
C. pneumoniae may be important in the pathogenesis of
diseases associated with this organism, including atherosclerosis.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Characterization of a Strain of Chlamydia
pneumoniae Isolated from a Coronary Atheroma by Analysis of the
omp1 Gene and Biological Activity in Human
Endothelial Cells
*
Corresponding author. Mailing address: Division of
Infectious Diseases, MDR Building, Room 622, Department of Medicine,
University of Louisville, Louisville, KY 40292. Phone: (502) 852-5132. Fax: (502) 852-1147. E-mail:
JTSUMM01{at}ulkyvm.louisville.edu.
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