Figure 7: Reprogrammed phage as kill switches.

(A) A V. cholerae-specific phage kill switch. Phage VP882 q::Tn5 (depicted as the multi-colored ring lacking the blue q gene) exists as a lysogen that is unable to lyse host cells. A functional copy of q, under a V. cholerae-specific promoter (PvqmR-q, depicted as the plasmid carrying the blue gene) is not activated in E. coli (left) because E. coli lacks VqmA, but is activated in V. cholerae that possesses VqmA (middle, blue waves showing Q production and yellow waves showing lysis,). ΔvqmA V. cholerae, by contrast does not activate q (right). We note that all three strains produce DPO. The key for this kill switch is the selective presence of VqmA_Vc only in the WT V. cholerae host. (B) Killing of WT V. cholerae and growth of ΔvqmA V. cholerae, WT V. parahaemolyticus, and WT V. vulnificus using the V. cholerae-specific targeting strategy from panel A. Relative colonies recovered is the number of exconjugant colonies obtained after the plasmid carrying PvqmR-q was introduced into the indicated strains compared to when a control plasmid was introduced. All strains carry phage VP882 q::Tn5 as a lysogen. (C) S. typhimurium-specific kill switch. Growth of S. typhimurium carrying a plasmid with aTc inducible hilD, the Pinvf-q kill switch, and phage VP882 harboring q::Tn5 (left two bars), inducible hilD and the Pinvf-q kill switch without phage VP882 q::Tn5 (middle two bars), inducible hilD and phage VP882 q::Tn5 without the PinvF-q kill switch (right two bars). Black; no aTc, white; 2 ng mL⁻¹ aTc. In B and C, data are represented as mean ± std with n=3 biological replicates. See also Figure S6.