Submitted to: Journal of Applied Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/27/2000
Publication Date: 9/7/2001
Citation: SHELBY, R.A., SHOEMAKER, C.A., EVANS, J.J., KLESIUS, P.H. DEVELOPMENT OF AN INDIRECT ELISA TO DETECT HUMORAL RESPONSE TO STREPTOCOCCUS INIAE INFECTION OF NILE TILAPIA, OREOCHROMIS NILOTICUS. JOURNAL OF APPLIED AQUACULTURE. 11(3) 2001 35-44 Interpretive Summary: Streptococcus iniae causes mortalities in cultivated tilapia as well as a number of other species important to US aquaculture. We developed an ELISA assay to monitor the presence of this disease in tilapia to replace the agglutination assay which has been in previous use. Briefly, this was accomplished by first developing an anti-tilapia immunoglobulin antibody in goats. Streptococcal antigen is coated onto a plastic ELISA plate, followed by the tilapia serum sample, goat antibody, enzyme conjugate, and finally a substrate which changes color to indicate the amount of antibody in the tilapia serum sample. This test can be used to determine the effectiveness of our vaccines or monitor natural disease occurrence.
Technical Abstract: The humoral antibody of tilapia (Oreochromis niloticus) to Streptococcus iniae infection was measured in two groups by an indirect enzyme linked immunoassay (ELISA). One treatment group was experimentally inoculated with S. iniae and the other consisted of a non-inoculated control. The antibody response of the experimental infected group was significantly different from the non-infected tilapia. The indirect ELISA utilized goat anti-tilapia IgM and a commercially available rabbit anti-goat IgG enzyme conjugate. The specificity of the antibody response was directed against cell-free sonicated antigen preparation from whole S. iniae ARS-98-60 cells. The ELISA results were highly correlated with the agglutination results for tilapia anti-S. iniae antibody.