Bacteriophage-bacteriophage interactions in the evolution of pathogenic bacteria

Many bacteriophages carry virulence genes encoding proteins that play a major role in bacterial pathogenesis. Recently, investigators have identified bacteriophage-bacteriophage interactions in the bacterial host cell that also contribute significantly to the virulence of bacterial pathogens. The relationships between the bacteriophages pertain to one bacteriophage providing a helper function for another, unrelated bacteriophage in the host cell. Accordingly, these interactions can involve the mobilization of bacteriophage DNA by another bacteriophage, for example in Escherichia coli, Vibrio cholerae and Staphylococcus aureus; the host receptor for one bacteriophage being encoded by another, as found in V. cholerae; and the presence of one bacteriophage potentiating the virulence properties of another bacteriophage, as found in V. cholerae and Salmonella enterica.