Identification of a Mamu Class I-restricted listeriolysin T-cell epitope in rhesus macaques infected with Listeria monocytogenes (LM) (129.13)

Abstract

Abstract LM is a gram positive foodborne pathogen that causes a flu-like illness in immunocompetent patients, but immunocompromised patients can develop septicemia and meningitis resulting in a high mortality rate. The primate model of LM infection is being used to investigate both innate and adaptive components of immunity in an animal model that is more relevant to human disease. Cytotoxic T lymphocytes were isolated from rhesus monkeys infected with LM by nasogastric intubation and used to identify Class I-restricted LM epitopes. Peptides were eluted from the surface of syngeneic B lymphocytes that were incubated overnight with heat-killed LM, and then peptides were separated by reversed-phase HPLC. An 11-mer peptide was identified that induced significant target cell lysis. The amino acid sequence of this peptide was determined by Edman degradation and confirmed by mass spectrometry. The sequence of this peptide encompassed amino acids 220-230 of the listeriolysin protein. Synthetic peptides were synthesized according to this sequence. The CTL responses induced by these peptides were comparable to the eluted native peptide.