Senior scientist, Centre for Vaccine Evaluation, Health Canada, Ottawa, Ontario
Application of Mass spectrometry in the Regulation of Influenza Vaccines
Current methods for quality control of inactivated influenza vaccines include determining the amount of hemagglutinin (HA), verifying neuraminidase (NA) enzymatic activity, and demonstrating that the levels of the contaminant protein ovalbumin are below a limit. The HA assays require the availability of strain-specific reference HA antigens and antibodies. We have been developing rapid alternative methods for vaccine analysis that provide HA, NA and contaminant-protein identification and quantitation. Enzymatically digested vaccine proteins are analyzed by LC–MSE and absolute quantification of the HA and NA antigens, other structural influenza proteins and chicken egg proteins is achieved by comparing the average intensity of their three most intense tryptic peptides (“Hi-3”) to those from a spiked reference protein. In pursuing the validation of this method, we have expressed a protein that contains “Hi-3” peptide sequences from proteins of interest (QCONCAT) as well as compared our results to other MS and antibody based methods. The results are wonderfully consistent, but not easily explained.