Evaluation of Pertussis Toxin Expression in B2 and THIJS Media

Wholecell pertussis vaccine (wP) has been imperative and highly effective in preventing childhood deaths due to pertussis. Pertussis toxin is one of the virulence factors of Bordetella pertussis in all available pertussis vaccines. wP production in Razi Vaccine and Serum Research Institute is according to bioreactor culture of B. pertussis strains in B2 medium. The aim of this study was to evaluate B. pertussis strain 509 PT production in B2 and ThalenIJssel (THIJS) media by Chinese Hamster Ovary (CHO) cell and enzymelinked immunosorbent assay methods (ELISA). In the current study, B. pertussis strain 509 was cultured in B2 and THIJS media. Six samples were taken during the log growth phase within 23 h intervals (triplicate). The growth rate was calculated using opacity and the quantification of cellassociated and released PT measured by ELISA and CHO cell assays. THIJS medium was significantly showed an increase in the bacterial growth rate. During the first 29 h, bacterial concentrations in B2 and THIJS culture medium were 19 and 29 IOU, respectively. In THIJS medium, greater amount of pertussistoxin production was cellassociated. In B2 medium, maximum cellassociated toxin by ELISA and CHO cell assays were in the ODs of 1.1 and 0.9 and for THIJS medium in the ODs of 1.6 and 1.1, respectively. B. pertussis strain 509 in THIJS medium produced higher cell mass and cellassociated pertussis toxin than that of B2. It can be used for the production of wholecell vaccine with higher pertussis toxin and accordingly using lower biomass per dose leading to the reduction of vaccine toxicity.