Characterization of the humoral immune response to a commercial staphylococcus aureus mastitis vaccine

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The objective of this thesis was to test the hypothesis that a commercial vaccine for bovine S. aureus mastitis fails to induce a humoral immune response in milk. Previous research indicates that IgG2 and IgM are the major antibodies that allow opsonization of S. aureus for phagocytosis and killing by neutrophils. Two studies were carried out. Firstly, antibody levels (IgG, IgG1, IgG2 and IgM) against S. aureus strains of the three serotypes thought to be responsible for the majority of S. aureus intramammary infection (IMI) in the United States were characterized in the serum and milk of dairy. Vaccinates had significantly higher IgG, IgG1 and IgG2 levels than controls against all three serotypes of S. aureus in serum. Vaccinates had significantly higher IgG levels than controls against two serotypes of S. aureus in milk. Secondly, antibody levels (IgG1, IgG2, IgM and IgA) against S. aureus in milk were characterized in mature dairy cows. Vaccination did not appear to increase any of the S. aureus subclasses in milk. Previous studies suggest that the vaccine fails to completely prevent S. aureus intramammary infection. The failure to detect IgG2 and IgM responses in milk may explain the failure of the vaccine to completely prevent S. aureus IMI.