Effect of plasmid-borne gene complementation on <i>S</i>. Typhi deletion mutants during competitive assays within macrophages.

aCI, competitive index. bThe wild-type counterpart is represented by the nalidixic acid-resistant wild-type S. Typhi (DEF566). cComplemented mutants all carry the low-copy-number cloning vector pWSK29 [36] harbouring the respective deleted gene or gene cluster. dData presented are the mean ± standard error of the mean of at least three independent experiments performed in duplicate, where the deletion mutants were mixed either with the wild-type strain or the respective complemented mutant during infection of human macrophages. Asterisks (*) represent CI values for mutants which are significantly different from 1 (P<0.05).