Intramammary and systemic immunological profile of dairy cows during the non-lactating and periparturient periods
Kerro Dego, O., R. A. Almeida, S. I. Headrick, M. J. Lewis, C. D. Young, B. E. Gillespie, L. J. Siebert, D. A. Luther, G. M. Pighetti, and S. P. Oliver.  2013.  Proc. Conference of Research Workers in Animal Diseases, 53P.

Streptococcus uberis intramammary infections (IMI) are increasingly prevalent particularly in dairy herds that have controlled contagious pathogens such as S. agalactiae. A classical approach to control infectious disease is through the use of effective vaccines, however, with bovine mastitis this has been proven particularly challenging. A critical and practical problem is to induce protective immune responses at times when dairy cows are highly susceptible to mastitis such as during the non-lactating and periparturient periods when S. uberis IMI are most prevalent. We vaccinated cows with S. uberis adhesion molecule (SUAM) and control cows with PBS on day -28, 0, +28, relative to dry-off. Serum samples collected immediately before each vaccination and at parturition were analyzed for presence of specific anti-SUAM antibodies and serum from SUAM-vaccinated cows were used in phagocytosis and adherence/internalization inhibition assays. Results showed a steady increase in specific antibody titers in the serum and milk of vaccinated cows, which peaked after each vaccination. Further testing, under in vitro conditions, determined that serum anti-SUAM antibodies exert protective effect by reducing adherence to and internalization of S. uberis into bovine mammary epithelial cells and by increasing phagocytosis by bovine macrophages. Antibody isotyping data of SUAM-vaccinated cows at parturition suggested IgG1/IgG2 ratio were adequate to support macrophage phagocytosis activity and this response may confer protection against S. uberis IMI. However, to truly assess the protective effect of S. uberis vaccination around dry-off intramammary and systemic immunological profiles should be evaluated for 30 days after parturition when associated hormonal changes influence protective immune responses of dairy cows.