Immunity & infection
Bacteriophage are abundant at sites of bacterial infection, but their effect on mammalian hosts is unclear. We have identified novel, pathogenic roles for filamentous Pf bacteriophage produced by Pseudomonas aeruginosa(Pa) in suppression of immunity against bacterial infection. Pf promote Pa wound infection in mice and are associated with chronic human Pa wound infections. Murine and human leukocytes endocytose Pf. This results in phage RNA production which triggers TLR3- and TRIF-dependent type-I interferon production, inhibition of TNF, and suppression of phagocytosis. Conversely, immunization of mice against Pf prevents Pawound infection. Together, these data indicate that Pf triggers maladaptive innate viral pattern-recognition responses that impair bacterial clearance. Vaccination against phage virions represents a novel strategy to prevent bacterial infection.