Numbers of lysogens susceptible to λVIR.

Five λKAN lysogenic colonies formed by the twelve resistant mutants were tested for their susceptibility to λVIR, as evaluated by a spot test assay. The rows shaded in green correspond to strains that maintain λVIR, whereas those shaded in red correspond to strains in which the phage was lost. For W2, different results were obtained in two replicate experiments. For W5, no lysogens were produced and their susceptibility thus could not be assayed.