Low levels of EF-P during infection promote Salmonella pathogenicity by inducing production of the MgtC virulence protein via consecutive proline codons at mgtP in the leader RNA21 but, at the same time, limit the pathogen’s proliferation inside host by decreasing production of the MgtB Mg2+ transporter via another consecutive proline codons in the mgtB coding region. This evidence concerns the gene TRIM25 and infection.