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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
Immunization with gp96 from Listeria monocytogenes-infected mice is due to N-formylated listerial peptides
A M Sponaas1, U Zuegel, S Weber
1Department of Immunology, Max-Planck Institute for Infection Biology, Berlin, Germany.
Abstract:
N-Formylated (N-f-met) peptides derived from proteins of the intracellular bacterium Listeria monocytogenes generate a protective, H2-M3-restricted CD8 T cell response in C57BL/6 mice. N-f-met peptide-specific CTL were generated in vitro when mice previously immunized with gp96 isolated from donor mice infected with L. monocytogenes were stimulated with these peptides. No significant peptide-specific CTL activity was observed in mice immunized with gp96 from uninfected animals. Masses corresponding to one N-f-met peptide were found by matrix-assisted laser desorption/ionization-mass spectrometry on gp96 isolated from C57BL/6 mice infected with L. monocytogenes, but not on gp96 from noninfected mice. Therefore, bacterial N-f-met peptides from intracellular bacteria can bind to gp96 in the infected host, and gp96 loaded with these peptides can generate N-f-met-peptide-specific CTL. We assume a unique role of gp96 in Ag processing through the H2-M3 pathway.
Insights
N-formylated peptides from Listeria monocytogenes trigger a protective CD8 T cell response. These bacterial peptides bind to gp96 in infected mice, enabling the generation of specific T cells via the H2-M3 pathway.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Intracellular bacteria like Listeria monocytogenes evade host immunity.
- CD8 T cell responses are crucial for clearing intracellular pathogens.
- The H2-M3 MHC class I molecule presents bacterial antigens.
Purpose of the Study:
- To investigate the role of N-formylated peptides in Listeria monocytogenes immunity.
- To determine if gp96 can present these bacterial peptides to T cells.
- To elucidate the mechanism of antigen presentation via the H2-M3 pathway.
Main Methods:
- Generation of N-formylated peptide-specific cytotoxic T lymphocytes (CTL) in vitro.
- Immunization of C57BL/6 mice with gp96 isolated from infected and uninfected mice.
- Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) to detect peptides on gp96.
Main Results:
- N-formylated peptides from L. monocytogenes induced H2-M3-restricted CD8 T cell responses.
- gp96 isolated from L. monocytogenes-infected mice, but not uninfected mice, presented N-f-met peptides.
- Peptide-specific CTL activity was observed only when mice were immunized with gp96 from infected donors.
Conclusions:
- Bacterial N-formylated peptides can bind to gp96 in infected hosts.
- gp96 loaded with these peptides can generate N-formylated peptide-specific CTL.
- gp96 plays a unique role in antigen processing and presentation through the H2-M3 pathway.
