To investigate the prevalence of T6SS-mediated bacterial virulence among V. cholerae, pandemic strains of the O1 serogroup were tested for virulence toward E. coli. Survival of E. coli prey was measured following exposure to V. cholerae predator strains V52, V52ΔvasK, El Tor N16961, and classical O395 in the killing assay, as described