Pertussis toxin-dependent and -independent protection by Bordetella pertussis against influenza

Area of Science:

• Immunology
• Microbiology
• Virology

Background:

• Bacterial-viral co-infections are common but their interactions remain unclear.
• Understanding these interactions is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the impact of Bordetella pertussis infection on influenza A virus (IAV) infection.
• To determine the role of pertussis toxin (PT) in this interaction.

Main Methods:

• Experiments were conducted using C57BL/6J mice and IL-17 knockout mice.
• Mice were infected with B. pertussis strains (BPSM, BPRA) with or without purified PT.
• Subsequent challenge with IAV allowed assessment of mortality, weight loss, and viral load.

Main Results:

• Prior B. pertussis infection (BPSM or BPRA) protected mice from IAV-induced mortality.
• Combined administration of BPRA and PT enhanced protection against weight loss and reduced viral load, correlating with increased IL-17A in lungs.
• Protection against viral replication was dependent on IL-17, whereas protection against mortality and weight loss was independent of IL-17 and PT.

Conclusions:

• B. pertussis infection confers protection against IAV through two pathways.
• One pathway involves PT and IL-17, leading to reduced viral replication.
• The second pathway, independent of PT and IL-17, protects against influenza disease severity without affecting viral load.