| Little is known about elasmobranch immune responses to microflora within the marine environment. Likewise, the ability of elasmobranchs to mount immune responses against specific marine bacteria remains uncharacterized. Developing antibodies against elasmobranch immunoglobulin M (IgM), C-reactive protein (CRP), and lysozyme is a first and critical step towards developing sensitive methods for quantifying specific and innate responses to bacteria in sharks. Specific antibodies against IgM can be used to measure both total and specific circulating IgM, and specific antibodies for CRP can be used to measure this acute phase protein as a possible indicator of acute inflammation. Antibody probes for lysozyme can be used to measure acute infection. Currently, there are no data describing what normal levels of shark IgM, CRP, or lysozyme should be, and if levels are different in animals living in habitats of differing environmental quality. Serum samples from 131 sharpnose sharks, Rhizoprionodon terraenovae, of both genders were collected from three different geographical regions along the coast of SC and GA, USA, between June and November. Sharpnose IgM was purified over a protein-A column, while C-reactive protein was purified sequentially over AH-sepharose 4B-PC and sepharose CL-4B columns. Balb/c mice were immunized with purified IgM and CRP for generating stocks of polyclonal anti-sera. A monoclonal antibody (M24-2) generated against mummichog (Fundulus heteroclitus) lysozyme that also recognizes sharpnose lysozyme was available from this laboratory. Total and bacteria-specific IgM, CRP, and lysozyme were quantified by ELISA. The sharpnose shark populations from Charleston, SC, when compared to Beaufort, SC and Brunswick, GA, had higher concentrations of total IgM and higher antibody titers against select marine bacteria. While the CRP concentrations were highest in the sharpnose shark population from Charleston, SC, compared to Beaufort, SC and Brunswick, GA, the lysozyme levels were lowest in the Charleston, SC population. With a seasonal comparison, concentrations of total IgM and higher antibody titers against select marine bacteria were higher in the fall in the Charleston, SC population, while CRP concentrations were higher in the summer. |
