Staphylococcus aureus ClfA-CTA2/B as a Primary Vaccine Candidate for Bovine Mastitis

Staphylococcus aureus (S. aureus) mastitis is one of the most common bacterial infections in dairy cattle. S. aureus is a gram-positive bacterial pathogen that infects the host by entering the udders and teat canals. The bacterium is contagious and does not respond to frontline antibiotics. S. aureus also has variation in strains that secrete a variety of toxins. A S. aureus vaccine would prevent the dependence of antibiotic treatment and increase the quality of the dairy milk. Clumping factor A (ClfA), a S. aureus adhesin, is a fibrinogen-binding factor found on the surface of S. aureus and is a promising vaccine candidate. In this project, we are combining the non-toxigenic CTA2/B from Vibrio cholerae with ClfA to form ClfA-CTA2/B fusions. Isolation of ClfA was performed using isolates of S. aureus related to MRSA 252. ClfA-CTA2/B chimeras are isolated from E. coli periplasm and purified using D-galactose agarose resin. An intranasal ClfA-CTA2/B chimera was used to vaccinate 21 dairy cows. Serum and milk samples were analyzed by ELISA for anti-ClfA IgG/IgA responses. Early results suggest that ClfA-CTA2/B vaccination produces ClfA specific antibodies