Infectious bursal disease virus inoculation infection modifies Campylobacter jejuni-host interaction in broilers

Area of Science:

• Avian immunology
• Bacterial pathogenesis
• Gut microbiota dynamics

Background:

• Campylobacter jejuni colonizes chickens, influenced by host immunity and gut microbiota.
• Infectious bursal disease virus (IBDV) causes immunosuppression, potentially exacerbating secondary infections.
• This study investigates how IBDV-induced immunosuppression affects C. jejuni pathogenesis in broiler chickens.

Purpose of the Study:

• To determine the impact of IBDV-induced immunosuppression on C. jejuni colonization and pathogenesis.
• To explore the role of timing between viral and bacterial infections on C. jejuni colonization.
• To assess the effect of co-infection on host immune responses and gut microbiota.

Main Methods:

• Broiler chickens were inoculated with a very virulent (vv) IBDV strain.
• C. jejuni was subsequently inoculated at different time points post-IBDV infection (7 or 9 days).
• Bacterial colonization (CFU counts), immune cell populations (B and T lymphocytes), and microbiota composition were analyzed.

Main Results:

• vvIBDV infection suppressed caecal B lymphocytes and anti-C. jejuni antibody response.
• Co-infection altered C. jejuni colonization patterns, with increased CFU in the early phase (Experiment A) and impaired clearance (Experiment B).
• No significant differences in lamina propria T lymphocytes were observed; however, both pathogens altered microbiota composition.

Conclusions:

• The timing of IBDV and C. jejuni co-infection influences C. jejuni colonization and clearance.
• Anti-Campylobacter antibodies are crucial for bacterial clearance, highlighting the impact of IBDV-induced immunosuppression.
• IBDV control strategies could indirectly benefit chicken gut health by reducing C. jejuni colonization and shedding in commercial flocks.