[Reproducibility of Fim2 and Fim3 antigens determination in Bordetella pertussis by serotyping method].

Introduction: Serotyping is a commonly used method to characterize the presence of Fimbriae 2 and 3 in Bordetella pertussis strains for epidemiological purposes and optimal choice of strain composition of the pertussis whole-cell vaccine. Monoclonal antisera against Fim2 and Fim3 are recommended to be used for microplate serotyping instead ofpolyclonal. Reliable evaluation offimbriae expressed by B. pertussis strains influence interpretation of vaccine-driven strain evolution.

Methods: To evaluate the impact of tests conditions on the reproducibility of serotyping, results of serotyping based on a standardized protocol for microplate agglutination with monoclonal antisera performed in three different accredited laboratories were compared. For the study isolates of three vaccine strains of B. pertussis deposited within seed lot system originating from different liofilization lots were compared.

Results: Lack of the complete agreement on serotyping results among three labs might relates to the differences of media used, subjective reading, test conditions, and specificity of the reagents.

Conclusions: Serotyping results should be interpreted with caution and the type of media and culture conditions used should be precisely recommended after validation studies. Inconsistent results should be confirmed using an alternative technique, eg. ELISA or by reference laboratory.