FPR1 and listeriosis: FPR1 deficiency results in increased bacterial burden and mortality in models of systemic Listeria monocytogenes infection but, despite this, the influence of FPR1 in pulmonary models of infection is unclear.7–10 Due to proposed evolutionary symbiosis mitochondrial-synthesised peptides within eukaryotic cells, similar to bacterial peptides, contain a formylated N-terminus and bind FPR1 with great affinity.11