Co-Infection of C3000 Esherichia coli with Bacteriophages MS2 and T7 or pX-174 Results in Differential Cell Lysis Patterns

Bacteriophages can be used as a model for studying the dynamics of viral co-infection in a susceptible host. Escherichia coli strain C3000 was chosen as a common, susceptible host to determine the effect of competition on the lifecycle of MS2 co-infected with Φ X-174 or T7. Strain C3000 expresses lipopolysaccharide, necessary for attachment of Φ X-174 and T7, and male sex pili necessary for the attachment of MS2. The C3000 strain was infected with MS2 and Φ X-174 or with MS2 and T7 at a multiplicity of infection (MOI) of 1 or 2. In general, MS2 coinfection with Φ X-174 or T7 resulted in an earlier incidence of lysis compared to single infection with MS2 or Φ X-174 alone. Also, decreased lytic time was greatest at a higher MOI in MS2 coinfection with Φ X-174 but this trend was reversed in MS2 co-infection with T7. In this case, decreased lytic time was greatest at the lower MOI. This indicated that the intracellular interactions of one phage affected the lifecycle of the other. The effect of MOI on lytic time was inconsistent across strains and varied between Φ X-174 and T7.