Avidity of anti-pertussis toxin antibodies is associated with symptomatic Bordetella pertussis infection in a novel controlled human infection model

The study examined the relationship between the maturation of antibodies against pertussis toxin and symptomatic Bordetella pertussis infection. Healthy adults were intranasally inoculated with live bacteria and monitored for symptom development. Blood samples were collected before inoculation and at 14, 28, 56, 180, and 365 days post-infection. Antibody avidity against pertussis toxin increased in both groups (20 symptomatic and 10 asymptomatic participants), peaked at day 56, and then declined. Symptomatic participants developed significantly higher levels of high and very high avidity antibodies at days 28, 56, 180, and 365 compared to asymptomatic individuals. The results suggest that avidity of antibodies against pertussis toxin may serve as an indicator of clinical disease outcome.