Molecular Differences Between Bordetella pertussis Circulating Strains and the Vaccine Strain Used for Vaccine production: Implication in the Efficiency of Pertussis Vaccine

GAILLARD M. EMILIA; SISTI FEDERICO; GRAIEB AUGUSTO; FERNÁNDEZ JULIETA; BOTTERO DANIELA; FINGERMANN MATÍAS; ROBERTS ROY M; PIANCIOLA LUIS; RICO OSVALDO; HOZBOR DANIELA

Baltilmore, USA

Congreso; The Tenth Annual Conference on Vaccine Research. National Foundation for Infectious Diseases; 2007

National Foundation for Infectious Diseases.

Background: Pertussis is re-emerging in several countries, despite ahigh vaccination coverage. It is suggested that antigenic divergencebetween vaccine strains and circulating strains has contributed to thisre-emergence. Here we analyzed the relevance of this divergence inprotection by using a respiratory model of B. pertussis infection inmice. Methods: To examine protective immunity we used the murineB. pertussis intranasal challenge model. Three-to-four-week-old Balb/cmice were immunized twice with pertussis vaccine either commerciallyobtained or prepared with clinical isolates at our lab. Then, mice wereintranasally challenged with sublethal doses of either B. pertussisvaccine strain or clinical isolates. Control animals were vaccinatedwith PBS. Two hours later and at day five and eight after the challenge,the lungs were collected for bacterial count. Results: As expected,significant differences between immunized animals and the control group were observed (p<0.001). Adequate elimination rates (p<0.005) were observed in mice immunized and challenged with the same strain. However, when mice were immunized with commercial wholecell pertussis vaccine and challenged with antigenic divergent clinical isolates, lower clearance efficiency was induced (p<0.001).Conclusions: The efficacy of whole cell vaccine seems to depend on the genotype relatedness between the strain used in vaccine production and the circulating bacteria.