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Primary human T-cell responses to the major outer membrane protein of Chlamydia trachomatis
A J Stagg1, W A Elsley, M A Pickett
1Antigen Presentation Research Group, Clinical Research Centre, Harrow, Middlesex, U.K.
Abstract:
The major outer membrane protein (MOMP) of Chlamydia trachomatis is the main candidate antigen for a synthetic vaccine against chlamydial infection. Antibodies to surface-exposed epitopes on MOMP neutralize chlamydial infectivity but little is known about T-cell recognition of the molecule. We have measured primary human T-cell responses to recombinant fragments of MOMP as well as to the whole organism and synthetic MOMP peptides. Using antigen-pulsed low density cells (LDC) we were able to stimulate proliferative responses with T cells from most naive individuals. This response was antigen dose dependent and displayed an absolute requirement for dendritic cells in the antigen-presenting cell (APC) population. Several T-cell epitopes were identified in MOMP and one which stimulated T cells from 80% of donors was resolved as a 12 amino acid synthetic peptide. Dual cell surface labelling and cell cycle analysis by FACS revealed that both CD4+ and CD8+ T cells were stimulated in these cultures. The fact that we were able to obtain proliferative responses and interferon-gamma (IFN-gamma) production to MOMP using cells from cord bloods confirmed that these are genuine primary responses. These experiments have identified a region on MOMP, to which T cells from most humans make a primary response, which may be useful in a chlamydial vaccine. The approach is useful for vaccine development in general.
Insights
Researchers identified a key region on the major outer membrane protein (MOMP) of Chlamydia trachomatis that elicits a primary T-cell response in most individuals. This finding is crucial for developing a more effective chlamydial synthetic vaccine.
Area of Science:
- Immunology
- Vaccinology
- Microbial Pathogenesis
Background:
- The major outer membrane protein (MOMP) of Chlamydia trachomatis is a primary target for a synthetic chlamydial vaccine.
- While antibodies against MOMP neutralize infectivity, T-cell recognition of MOMP remains poorly understood.
Purpose of the Study:
- To investigate primary human T-cell responses to Chlamydia trachomatis MOMP.
- To identify T-cell epitopes within MOMP for potential vaccine development.
Main Methods:
- Utilized antigen-pulsed low-density cells (LDCs) to stimulate T cells from naive individuals.
- Employed recombinant MOMP fragments, whole organism, and synthetic peptides for T-cell stimulation.
- Confirmed primary responses using cord blood cells, assessing proliferation and interferon-gamma (IFN-γ) production.
- Characterized T-cell populations (CD4+ and CD8+) using flow cytometry.
Main Results:
- Identified several T-cell epitopes within MOMP.
- Discovered a 12 amino acid peptide that stimulated T cells from 80% of donors.
- Demonstrated dose-dependent responses requiring dendritic cells as antigen-presenting cells.
- Confirmed genuine primary T-cell responses through proliferation and IFN-γ production in cord blood cells.
Conclusions:
- A specific region of MOMP elicits a primary T-cell response in the majority of the human population.
- This identified MOMP region holds potential for enhancing chlamydial vaccine efficacy.
- The methodology used is broadly applicable to vaccine development research.