Immunopeptidome Landscape During Brucella melitensis Infection in Mice

Area of Science:

• Immunology
• Microbiology
• Proteomics

Background:

• Dendritic cells (DCs) are crucial antigen-presenting cells (APCs) in initiating adaptive immune responses.
• Brucella melitensis is a significant intracellular pathogen that evades host immunity.
• Understanding the bacterial antigens presented by DCs is key to developing effective vaccines.

Purpose of the Study:

• To characterize the immunopeptidome of Brucella melitensis M5+gfp presented by MHC class II molecules on mouse bone marrow-derived dendritic cells (BMDCs).
• To identify the source proteins of these presented peptides and assess their diversity.
• To provide a foundation for novel Brucella melitensis vaccine strategies.

Main Methods:

• In vitro infection of BMDCs with recombinant Brucella melitensis M5+gfp.
• Isolation of the immunopeptidome using hypotonic lysis and co-immunoprecipitation (Co-IP).
• Characterization of peptides via liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Main Results:

• Successfully identified 289 MHC-II-bound Brucella melitensis M5+gfp peptide sequences.
• These peptides mapped to 183 distinct bacterial proteins, demonstrating broad coverage.
• Source proteins were abundant and functionally diverse, not limited to surface antigens.

Conclusions:

• Brucella melitensis presents a diverse immunopeptidome via MHC-II on infected BMDCs, originating from a wide array of proteins.
• This comprehensive presentation offers multiple targets for host immune recognition and T-cell activation.
• The findings support the development of targeted Brucella melitensis subunit vaccines and advance immunopeptidome analysis techniques.