Opsonic antibodies are critical to prevent Bordetella parapertussis survival to PMN phagocytosis. Current whopping cough vaccines do not induce these kind of antibodies

GORGOJO, J; LAMBERTI, Y; ALVAREZ HAYES, J; VALDEZ, H; RODRIGUEZ, ME

Buenos Aires, Argentina

Congreso; First French-Argentine Immunology Congress (FAIC). LVIII reunion Annual de la Sociedad Argentina de Inmunología.; 2010

SOCIEDAD ARGENTINA DE INMUNOLOGIA

B. pertussis (Bp) and Bordetella parapertussis (Bpp) are the etiologic agents of whooping cough, a human disease that is re-emerging despite high vaccination coverage with Bp vaccine. Bpp showed an increasing impact in the epidemiology of this disease whose start roughly concurs with the introduction of the acellular vaccine against Bp. We recently found that Bp vaccine has a poor efficacy against Bpp. O-antigen of Bpp interfere with Bpp binding Bp–induced antibodies. Importantly, this detrimental effect is particularly drastic in the case of Bp acellular vaccine induced antibodies. In previous studies we showed that the lack of antibody opsonisation of Bp leads to the fail of bacterial killing by immune cells. We hypotheses that Bpp has a similar immune subversion mechanism which, in the absence of proper opsonins, allows it to evade immune clearance by PMN. We used GFP bacteria and fluorescent probes to investigate PMN uptake and intracellular trafficking of B. parapertussis in the presence and the absence of opsonic antibodies by mean of flow citometry and confocal microscopy. Intracellular bacterial survival was evaluated by Polymyxin B protection assays. Means were compared using ANOVA or t-Student (p<0.05), depending on the study. In the absence of antibodies Bpp was efficiently phagocytosed by PMN but only 14 ± 4% of the intracellular bacteria were found in acidic vacuoles (lysotracker positive) indicating that most of the bacteria remained in non-killing vacuoles as confirmed by intracellular viable counts. The presence of anti-Bpp but not anti-Bp antibodies increased 2 times PMN bacterial uptake as well as the trafficking of Bpp to lisosomal compartment (26 ± 5% of colocalization) leading to significantly more efficient bacterial killing as confirmed by intracellular viable counts. These data suggest that Bp vaccines induce antibodies that failed to opsonize Bpp leading to a defective immune clearance eventually enabling bacterial survival in the host