Effect of hydromechanical stress on cellular antigens of Bordetella pertussis

Effect of relevant culture parameters on Pertussis Toxin expression by Bordetella pertussis

Whooping cough vaccines are produced using different ranges of cultivation conditions and medium compositions, which are known to influence growth rate, virulence factor production and degradation, as well as the virulence factors' association to the cell. This study quantifies the impact of individual parameters on Pertussis Toxin (PT) production, using an optimized chemically defined medium as starting point, rather than a complex medium. A number of chemicals that are identified affect both growth rate and virulence factor production, which occur at similar levels in various commonly used production media. Also, degradation by proteolytic activity is shown to be an important parameter to monitor, since it significantly affects the PT yield. Low sodium concentrations, i.e. 50-75 mM rather than the conventional 100-140 mM, significantly increase the growth rate of the organism, the final optical density, as well as the association of PT to the cells. The absolute amount of biomass produced measured as dry weight, is similar for all sodium concentrations tested, contrary to earlier work. While it is known that high iron concentrations inhibit virulence factor production, it is shown here that iron-limited growth results in very high specific PT production. This finding may be used to produce a whole-cell vaccine with little biomass per dose, reducing whole-cell vaccine toxicity. The Bordetella pertussis strain 509 used here produces 30% more PT at 34 than at 37 degrees C, a commonly used cultivation temperature. The data in this study show that existing production processes for cellular and acellular vaccines can in principle be optimised considerably by taking simple measures.

Whole-bacterial cell enzyme-linked immunosorbent assay for cell-bound Moraxella bovis pili

Infectious bovine keratoconjunctivitis (IBK), caused by Moraxella bovis, is a disease of major importance in cattle industry. M. bovis has several virulence factors among which pili are crucial antigen for the protective capacity of vaccines against this disease. The production of vaccines against IBK therefore requires a reliable technique for cellular piliation level assessment on cells to be included as vaccine components. In this study we describe a specific whole-bacterial cell enzyme-linked immunosorbent assay (bact-ELISA) capable of detecting pili antigen on M. bovis cell surface. A sequential competitive bact-ELISA was developed using highly piliated M. bovis cells as antigen. Samples to be analyzed were allowed to react with anti-pilus serum prior to incubation in wells coated with piliated cells of M. bovis. This assay proved useful for the rapid, sensitive and reproducible evaluation of piliation on M. bovis cells, and represents an important tool for cellular piliation monitoring daburing M. bovis cells production in stirred bioreactors.