Comparative Immunology Reports · Published 2026-06-30 · DOI 10.1016/j.cirep.2026.200298
Kursten A. Spegar, Patricia A. Fair, John P. Hawke, Dorian S. Houser, Adam M. Schaefer, John S. Reif, Charles D. Rice
The immune system is essential to fighting infections and disease and vital to the overall health of marine mammals. Previous studies in bottlenose dolphins have investigated immune responses to a wide variety of microorganisms. However, none have measured the levels of circulating antibodies against Streptococcus agalactiae, an emerging pathogen of concern for animal health. Our studies compared wild and managed populations of dolphins. Serum samples were collected from bottlenose dolphins from professional-care populations at the Georgia Aquarium (n = 34 between 2011 and 2012) and the United States Navy Marine Mammal Program (n = 63 between 2011–2012), as well as from wild dolphins in Charleston Harbor, South Carolina (n = 80 from 2003–2013), and the Indian River Lagoon, Florida (n = 163 from 2003–2015). We demonstrated that circulating antibodies from bottlenose dolphins recognize two proteins from S. agalactiae lysates via SDS-PAGE and immunoblotting. Relative serum titers were compared to antibody activities in all samples, as well as by population and year of sampling. Although titer data correlated well with activities, the latter were more sensitive in identifying differences. Serum antibody activities were higher in samples from the Indian River Lagoon compared to other populations. Notably, professional-care dolphins showed lower levels of antibody activities against S. agalactiae than wild dolphins. Previous studies examining select bottlenose dolphin responses to other marine bacteria demonstrate that the environment is a significant factor influencing bottlenose dolphin health. Samples from the Indian River Lagoon and our results are consistent with those studies, but notably lower titers than to previously examined pathogens.
Abstract from DOAJ. Public domain (CC0 1.0).
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Spegar, K., Fair, P., Hawke, J., et al. (2026). Circulating antibody responses against Streptococcus agalactiae in wild and professional-care bottlenose dolphins, Tursiops truncatus: A baseline study for future surveillance. Comparative Immunology Reports. https://doi.org/10.1016/j.cirep.2026.200298