SPI1 and infection: The Lon protease plays a key role in Salmonella virulence, as it regulates the expression of virulence genes located in Salmonella pathogenicity Island I (SPI-1) during the early stages of systemic infection.5 It does not seem to have a crucial impact on SPI-2 genes, which are regulated during later phases of infection.7 Lon protease is shown to potentiate bacteria evolution and antimicrobial resistance.8 The dysregulation of Lon protease, a negative regulator of SPI-1 genes, leads to increased expression and orchestration of early virulence genes.