Identification of CT521 as a frequent target of Th1 cells in patients with urogenital Chlamydia trachomatis infection.
BACKGROUND
The human immune response to a Chlamydia trachomatis serovar D lysate was investigated in patients with urogenital C. trachomatis infection, to identify novel T cell targets.


METHODS
A C. trachomatis lysate was fractionated on the basis of molecular mass, and each fraction was used to stimulate peripheral-blood mononuclear cells from patients with C. trachomatis infection. In frequently recognized fractions, proteins were identified by mass spectrometry, recombinantly expressed, and tested for T cell recognition.


RESULTS
T cell recognition of the fractions was highly heterogeneous in patients with C. trachomatis infection (n=16). Four patients exhibited responses that were strongly targeted to antigens of 16-20-kDa molecular mass. Three proteins were identified in this fraction: CT043, CT511, and CT521. The T cell response to the individual recombinant proteins were investigated, and CT521 was found to induce the highest level of interferon (IFN)- gamma. The recognition of CT521 was investigated in a larger study population (n=41), and a positive IFN-gamma response was measured in 83% of the patients. Several T cell epitopes were identified in CT521; in particular, peptide 5 in the central part of the protein was frequently recognized by T cells (63%).


CONCLUSIONS
We have identified a novel C. trachomatis antigen, CT521, that is frequently recognized in patients with urogenital C. trachomatis infection.
Olsen
Anja Weinreich
AW
Chlamydia Research, Department of Infectious Disease Immunology, Statens Serum Institute, DK-2300 Copenhagen S, Denmark. Aol@ssi.dk
Follmann
Frank
F
Jensen
Klaus
K
Højrup
Peter
P
Leah
Robert
R
Sørensen
Hanne
H
Hoffmann
Steen
S
Andersen
Peter
P
Theisen
Michael
M
D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology; D002690:Chlamydia Infections / Q000276:immunology*; D002692:Chlamydia trachomatis / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D052776:Female Urogenital Diseases / Q000382:microbiology; D006801:Humans; D008297:Male; D052801:Male Urogenital Diseases / Q000382:microbiology; D018417:Th1 Cells / Q000502:physiology*
D000942:Antigens, Bacterial; D018984:Epitopes, T-Lymphocyte