Evaluation of anti-Erysipelothrix rhusiopathiae IgG response in bottlenose dolphins (Tursiops truncatus) to a commercial pig vaccine

Erysipelothrix rhusiopathiae is the causative agent of erysipeloid in humans and of erysipelas in various animals, including bottlenose dolphins (Tursiops truncatus) in which an infection has the potential to cause peracute septicemia and death. The purpose of this study was to evaluate the efficacy of using an off label porcine (ER BAC PLUS®, Zoetis Inc.) Erysipelothrix rhusiopathiae bactrin in a bottlenose dolphin vaccination program by determining the anti-E. rhusiopathiae antibody levels in vaccinated dolphins over a 10 year period. Serum samples (n = 88) were analyzed using a modified fluorescent microbead immunoassay from 54 dolphins, including three with no history of vaccination, 51 dolphins with an average of five vaccinations, three of which had previously recovered from a natural E.rhusiopathiae infection. A mean 311-fold increase in IgG antibody index was measured in a subsample of ten dolphins 14 d after the first booster vaccination. Serum IgG antibodies titers were influenced by number of vaccines received (r2 = 0.47, p < 0.05), but not by age, gender, history of natural infection, adverse vaccine reaction, vaccination interval or time since last vaccination. The commercial pig bacterin was deemed effective in generating humoral immunity against E.rhusiopathiae in dolphins. However, since the probability of an adverse reaction toward the vaccine was moderately correlated (p = 0.07, r2 = 0.1) with number of vaccines administered, more research is needed to determine the optimal vaccination interval.