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Functionally Effective Immune Responses of Dairy Cows Vaccinated with Streptococcus uberis Adhesion Molecule during the Transition Period

Streptococcus uberis causes a significant proportion of mastitis in dairy cows. It is very important to induce protective immunity during the perparturient (transition) period when dairy cows are highly susceptible to mastitis. The aim of this study was to optimize immune responses of dairy cows during the periparturient period through three vaccinations at 28 days before drying off (D-28), at drying off (D0), and at 28 days after drying off (D+28) with recombinant Streptococcus uberis adhesion molecule (rSUAM). Forty dairy cows in the 1st or 2nd lactation were divided into two groups of 20 cows each. Cows in Group 2 were vaccinated with 200 μg of rSUAM with Montanide® ISA70VG adjuvant whereas cows in Group 1 (control) were injected with Montanide® ISA70VG mixed with PBS. Blood and milk samples were collected before each vaccination and at calving and were analyzed for anti-rSUAM IgG, IgG1, IgG2, IgA and IgM antibodies. Serum from rSUAM vaccinated cows was used in phagocytosis, as well as attachment and internalization inhibition assays. Results showed that serum and milk anti-rSUAM IgG, IgG1, IgG2, IgA and IgM titers were significantly increased after each vaccination achieving highest titers after 3rd vaccination (P< 0.01). Anti-rSUAM antibodies were effective in reducing adherence to and internalization of S. uberis into primary bovine mammary epithelial cells as well as increasing phagocytic killing of S. uberis by bovine macrophages. Results showed that this vaccination schedule induced robust serum and milk anti-rSUAM immune responses during periparturient period that can be protective against S. uberis mastitis.