“Molecular differences between Bordetella pertussis circulating strains and the vaccine strain used for vaccine production: implication in the efficiency of pertussis vaccine induced immunity against currently circulating B. pertussis isolates”.

GAILLARD M.EMILIA; SISTI FEDERICO; FERNANDEZ JULIETA; BOTTERO DANIELA; GRAIEB AUGUSTO; FINGERMANN MATÍAS; HOZBOR DANIELA

Pinamar. Argentina

Congreso; XLI Reunión de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (Saib). Congreso; 2005

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (Saib)

Pertussis is among  the eight most common causes of death from infectious disease worldwide. Immunization is the most effective method for the prevention and control of pertussis and has been used successfully for decades. However, during the past 15 years, a resurgence of pertussis has also been seen in countries with high vaccination coverage of whole-cell vaccines. One explanation for this increasing incidence is the antigenic divergence between vaccine strains and circulating strains. In agreement with this hypothesis we have already characterized 48 Bordetella pertussis isolates obtained from pediatric patients. Our previous results showed that B. pertussis circulating bacteria were different from the strain used for vaccine production and similar to those previously found responsible for most pertussis outbreaks in other parts of the world, however the relevance in protection of this divergence has not been yet evaluated. In this study we applied a respiratory model of B. pertussis infection in mice via intranasal challenge as a predictive model of protection to test the ability of the currently used pertussis vaccine to eliminate Argentinean circulating strains. The challenge was performed using sublethal doses of either B. pertussis vaccine strain or clinical isolates. As control we used animals vaccinated with PBS. As expected, significant differences between the vaccine treated animals and the control group at all time points (p<0,001) were observed. These studies also showed lower potential of immunity induced by whole-cell pertussis vaccination in elimination rates of any of the clinical B. pertussis isolates assayed from the lungs, compared to vaccine strain (p<0,001). To detect any differences in bacterial protein expression that may be responsible for the failure in protection against the circulating isolates we performed immunoblot experiments. For these assays we employed whole cell lysates of clinical isolates as antigens and sera either from mice infected with different clinical isolates or from infected humans. The results showed clear differences between the immunological pattern of the distinct clinical isolates which were more prominent between two B. pertussis isolates. Two dimensional gel electrophoresis corroborated this results and currently the differential spots are being identified by MALDI TOF.