Gentamicin protection assay of complemented and wild type strains of S. Typhi. HEp-2 cells were grown and infected with the S. Typhimurium 14028s, S. Typhi STH2370 or the respective S. Typhi complemented strains. The recovered CFUs were counted 3 h post-infection. The values correspond to the means ± SD of three different experiments, each performed in triplicate. The CFUs recovered from infected cells with S. Typhi with each empty plasmid (pSU19 or pCC1) showed no differences with respect to the wild type strain (data not shown).