Therefore, we used the JE1134 strain as an ‘experimental’ chassis to compare the ability of T7 WT and T7 Δgp5.7 to lyse JE1134 cells to determine and provide further evidence that the repression of host RNAP activity by both Gp2 and Gp5.7 is required for optimal development of T7 in Ec. Results revealed that, in marked contrast to T7 WT, which lysed the JE1134 cells ∼70 min after infection, the T7 Δgp5.7 phage failed to detectably lyse JE1134 cells even after 120 min after infection (Figure 5C). This evidence concerns the gene GP2 and infection.