Objective: To use proteomic analysis to identify qualitatively and quantitatively mammalian protein components of commercial veterinary vaccines against canine distemper, leptospirosis, borreliosis, and rabies.
Sample: 25 licensed veterinary vaccines (from 4 different manufacturers) against canine distemper and leptospirosis, borreliosis, and rabies (3-year and 1-year durations of immunity).
Procedures: Duplicate samples from a single-lot vial of each vaccine were prepared by acetone precipitation and proteolysis with trypsin and Lys-C protease mix. Peptides mixtures (1 μg) were analyzed by liquid chromatography-tandem mass spectrometry using an Orbitrap Fusion Lumos mass spectrometer. Liquid chromatography-tandem mass spectroscopy data were searched against a Bos taurus protein database using MaxQuant to identify and quantify mammalian proteins in the vaccines. Identified proteins were classified by function and network analysis to visualize interactions.
Results: The largest number of mammalian proteins was identified in 3-year rabies vaccines (median, 243 proteins; range, 184 to 339 proteins) and 1-year rabies vaccines (median, 193 proteins; range, 169 to 350 proteins). Borrelia and leptospirosis-distemper (L&D) vaccines had the lowest number of proteins. Rabies vaccines had the highest number of identified proteins in common (n = 316); 33 were unique to 1-year products and 44 were found in 3-year products. Borrelia and L&D vaccines had 16 and 22 uniquely identified proteins, respectively. The protein classifications were primarily modulators of protein-binding activity, enzymes, transfer-carrier proteins, cytoskeletal proteins, defense-immunity proteins, calcium-binding proteins, and extracellular matrix proteins.
Clinical relevance: This study demonstrates proteomics application to evaluate quality differences among different vaccines, identifying potential stimulants of desirable and undesirable immune responses.