# Immunopeptidomics-based design of mRNA vaccine formulations against Listeria monocytogenes

## TL;DR

The paper presents a new mRNA vaccine approach against Listeria monocytogenes by identifying bacterial antigens presented on infected cells.

## Contribution

The study identifies novel Listeria antigens using immunopeptidomics and demonstrates their potential as mRNA vaccine candidates.

## Key findings

- 68 Listeria immunopeptides from 42 bacterial proteins were identified using immunopeptidomics.
- mRNA vaccines encoding these antigens induced protective CD8+ T-cell responses in mice.
- The findings offer a foundation for developing clinical vaccines against Listeria.

## Abstract

Listeria monocytogenes is a foodborne intracellular bacterial pathogen leading to human listeriosis. Despite a high mortality rate and increasing antibiotic resistance no clinically approved vaccine against Listeria is available. Attenuated Listeria strains offer protection and are tested as antitumor vaccine vectors, but would benefit from a better knowledge on immunodominant vector antigens. To identify novel antigens, we screen for Listeria peptides presented on the surface of infected human cell lines by mass spectrometry-based immunopeptidomics. In between more than 15,000 human self-peptides, we detect 68 Listeria immunopeptides from 42 different bacterial proteins, including several known antigens. Peptides presented on different cell lines are often derived from the same bacterial surface proteins, classifying these antigens as potential vaccine candidates. Encoding these highly presented antigens in lipid nanoparticle mRNA vaccine formulations results in specific CD8+ T-cell responses and induces protection in vaccination challenge experiments in mice. Our results can serve as a starting point for the development of a clinical mRNA vaccine against Listeria and aid to improve attenuated Listeria vaccines and vectors, demonstrating the power of immunopeptidomics for next-generation bacterial vaccine development.

Currently, no approved vaccines for Listeria monocytogenes are available. Here, the authors use immunopeptidomics to map bacterial peptides presented on infected cells and identify antigens that, as mRNA vaccine, provide protection in mice.