Quantitative determination of bioactive proteins in diphtheria tetanus acellular pertussis (DTaP) vaccine by liquid chromatography tandem mass spectrometry.

A liquid chromatography tandem mass spectrometry method (LC-MS/MS) was developed to determine simultaneously the bioactive proteins including pertussis toxin (PT) subunits, filamentous hemagglutinin (FHA), pertactin (PRN) and fimbriae (FIM) in diphtheria, tetanus and acellular pertussis combined vaccine (DTaP). The trypsin digestion conditions were investigated in detail using PT reference to achieve satisfactory results in detection of the peptides on LC-MS/MS with a Bio-C18 column. The performance of the described method was evaluated using reference proteins and the results showed a wide linear range (0.15-24 ng μL-1), a high sensitivity (0.038 ng. μL-1 for FHA) and a good precision (RSD of peak area <3.3%). This novel LC-MS/MS method was applied to determine PT subunits, FHA, PRN and FIM in DTaP vaccines, a total of ten batches, obtained from five manufacturers. The results revealed clearly that batch-to-batch consistency of the DTaP vaccines in terms of the protein amounts was stable, while those from manufacturers were varied significantly. On the other hand, the amount of bioactive proteins in component DTaP vaccines was generally higher than those in co-purified DTaP vaccines. The described LC-MS/MS method was compared with Chinese Pharmacopeia method (Lowry method) and it was found that FHA and PRN amounts measured by the two methods were in good agreement. The LC-MS/MS method could provide the amounts of PT subunits. However, the Lowry method could not differentiate the subunits. The LC-MS/MS method was not only more selective and sensitive, but it can be used to determine simultaneously different bioactive proteins in complex matrix-formulated vaccines. The method was extended successfully in other purposes, such as the effect of detoxification on bioactive proteins and characterization of PT references from four organizations worldwide.