Analyses of cytotoxicity HT-29 infected with complemented and wild type S . Typhi strains. H T-29 cells were grown in transwells for 12-15 days. Polarised HT-29 cells were apically infected with the S. Typhi wild type or the respective complemented strains. Released LDH was measured 3 h post-infection and reported as percentage relative to the S. Typhi wild type. The values correspond to the means ± SD of three independent experiments, each performed in duplicate. The percentages of each S. Typhimurium 14028s, S. Typhi STH2370/pNT005 and S. Typhi STH2370/pNT006, have significantly differences respect S. Typhi STH2370 wild type. LDH release from infected cells with S. Typhi carrying empty plasmid (pSU19 or pCC1) showed no differences with respect to the wild type strain (data not shown).