Fig 3.

Assessment of SPI-6 T6SS contribution to replication in macrophage cell culture. Intracellular replication of SPI-6 T6SS mutants in RAW 264.7 murine macrophage-like cells expressed as a fraction of that of the wild type (WT) at 24 h postinfection compared with that of a ΔsseC SPI-2 T3SS translocon mutant (*, P < 0.05). Decreased intracellular replication of core gene ΔsciG and ΔsciS mutants was observed, with near-wild-type levels for the sciG complemented strain. Replication defects were also observed in noncore gene cluster 1 and 3 mutants. Decreased intracellular replication for the STM0278 mutant was observed when single gene mutants were tested, while a nonsignificant increase in that of individual noncore gene cluster 3 mutants was observed.