No Needles Required: Repurposing Bacterial Toxins as Vaccines
Mastitis is an inflammatory disease affecting udders of dairy animals across the globe. Animals that develop mastitis must be removed from herds for treatment, which can be a devastating burden to families who depend on small dairy herds for income and/or sustenance. Staphylococcus aureus is implicated as a major cause of mastitis. Development of a vaccine against S. aureus could drastically reduce the number of antibiotics being administered to dairy animals and prevent the loss of animals to mastitis.
Cholera toxin has two subunits: a receptor-binding (B) subunit and a catalytically active (A) subunit. B subunits are non-toxic but readily interact with immune cells. We exploit this characteristic by supplanting toxic A subunits with other proteins to create potent vaccines. We have conjugated two S. aureus virulence factors to the non-toxic cholera toxin B subunit. Recent results indicate that this vaccine can reduce bacterial shedding in milk and induce antigen-specific immune responses. By immunizing animals against these antigens, we hope to prevent establishment of S. aureus infection and to dramatically reduce the incidence of mastitis among dairy herds.