T4 Bacteriophage Dominates T7 Bacteriophage During Co-infection of Escherichia coli C600

Co-infection is the simultaneous infection of a host cell by multiple viruses. It can result in complex competitive interactions that have significant consequences on virulence and disease dynamics. Our study investigated the intracellular mechanisms utilized for viral competition and identified a dominant virus during co-infection with a T4 and T7 bacteriophage model in E. coli strain C600. The co-infection was performed under two different input multiplicity of infection (MOI) conditions, each favouring one phage type. The amount of infectious progeny from coinfected samples was assessed with plaque assays. Results indicated that T4 dominated in both conditions, whereas PCR data showed T7 amplification from samples that produced only T4 plaques. We speculate that the dominance exhibited by T4 is due to its ability to modify the host RNA polymerase to only transcribe its own genes, thereby inhibiting T7 early gene transcription. In conclusion, bacteriophage T4 exhibited viral dominance over T7 during co-infection of E. coli C600, via mechanisms that interfered with T7 maturation.