The Influence of Environmental Health Indices on Antibody Responses Against \u3ci\u3eStreptococcus agalactiae\u3c/i\u3e in Bottlenose Dolphins, \u3ci\u3eTursiops truncatus\u3c/i\u3e

The common bottlenose dolphin, Tursiops truncatus, is one of the most recognized marine mammal species. These mammals now serve as a sentinel species to evaluate and monitor ecosystem health in critical coastal regions. For example, the Atlantic bottlenose dolphin health and environmental risk assessment project (HERA) has studied these animals over the past 20 years from the Charleston harbor in South Carolina (CH) and the Indian River Lagoon (IRL) in Florida, USA, as part of an overall approach to understanding links between Oceans and Human Health (OHH). Environmental pressures, assessed as a combination of pollution exposure, habitat quality, and exposure to infectious diseases, are now considered the primary driver for the health of dolphins. Specifically, emerging infectious diseases and zoonotic pathogens have become a serious and complex threat to humans, animals, and environmental health. Streptococcus agalactiae is an emerging environmental disease that can also affect immunocompromised humans. One means to assessing exposure to such diseases is by examining seroconversion or seropositivity. Serum antibody levels have seldom been used with environmental species because of the general lack of immunological reagents and the intense labor associated with these methods. In this study, monoclonal antibodies (mAb) were generated against bottlenose dolphin IgG, IgM in bull shark (Carcharhinus leucas) and spotted eagle ray (Aetobatus narinari), and an on-hand mAb against loggerhead sea turtle (Caretta caretta) IgY was used. Serum or plasma samples were collected from animals inhabiting the same location. These reagents were used to calculate relative antibody titers against S. agalactiae at a dilution of 1:200 and compare these data to antibody activities calculated over a range of serum dilutions. This part of the study demonstrates that antibody activity data are more sensitive than simple relative titers when determining antibody responses to S. agalactiae in all four species and across the immunoglobulin spectrum (IgM, IgY, and IgG) of marine aquatic vertebrates. The generated monoclonal antibody against bottlenose dolphin IgG was used to compare relative titers to antibody activities in bottlenose dolphin serum samples collected over the past 20 years of the HERA project to compare Charleston Harbor animals to Indian River Lagoon animals. Responses in animals from the GA Aquarium and the managed marine mammal program (US Navy) were also examined. There were few differences between the groups in terms of relative antibody titers against S. agalactiae, but calculated antibody activity data demonstrate differences. Previously published studies from our lab demonstrate differences in antibody responses against several other highly pathogenic bacteria when comparing the dolphin groups over the years. Compared to those data, it appears that bottlenose dolphins are not currently burdened by S. agalactiae, and the managed US Navy and GA Aquarium populations are very healthy