Transfer of T6SS from Gallinarum to Typhimurium Lacking T6SS Complements its Colonization Defect in Mice.

genus harbors five Type VI Secretion System (T6SS) gene clusters. The T6SS encoded in SPI-6 (T6SS) contributes to Typhimurium colonization of chickens and mice, while the T6SS encoded in SPI-19 (T6SS) of Gallinarum contributes to chicken colonization. Interestingly, the T6SS of Gallinarum complemented the defect in chicken colonization of a Typhimurium strain that lacks the T6SS, suggesting that both T6SSs are interchangeable. Here we show that the transfer of Gallinarum T6SS complemented the defect in mice colonization of a Typhimurium ΔT6SS strain, indicating that both T6SSs are functionally redundant during host colonization.