John C. Jones; Bobby L. Middlebrooks; Rhonda A. Patterson
An enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies against Erysipelothrix rhusiopathiae in cetacean serum. Two different capture antigens have been evaluated for use in this ELISA. These capture antigens were (1) Frasch extracted surface antigens from a wild isolate of E. rhusiopathiae (designated Navy isolate) cultured from a deceased Pacific bottlenose dolphin (Tursiops gilli) and (2) SDS-PAGE purified 64 kDa surface proteins from the Navy isolate E. rhusiopathiae (designated N64K).1,2
Initial analysis of these assays was conducted using rabbit antisera specific for the Navy isolate E. rhusiopathiae. The indicator system used for both assays consisted of commercially available biotin labeled anti-rabbit IgG, alkaline phosphatase-labeled avidin and p-nitrophenyl phosphate (a chromogenic substrate). The ELISA titers were then compared to titers obtained using a passive agglutination assay.3 The passive agglutination assay was performed by mixing latex beads coated with purified N64K with dilutions of antiserum, shaking gently and assigning a titer as the highest dilution showing agglutination of the beads.
The titer obtained using the Frasch extracted surface antigens was the highest, greater than 1:102,400, while the ELISA using N64K as a capture antigen exhibited a titer of 1:200. The latex agglutination assay performed on the same sera gave a titer of 1:800.
Future studies will investigate the use of these assays as routine diagnostics for detecting E. rhusiopathiae exposure in cetacean serum.
1. Frasch; C. 1979. Noncapsular Surface Antigens of Neisseria meningitidis. In Seminars in Infectious Diseases, Vol. 2. Weinstein, L. and B. Fields, editors. Stratton Intercontinental Medical Book Corporation, N.Y. 304-337.
2. Groschup, M., K. Cussler, R. Weiss and J. Timoney. 1991. Characterization of a protective protein antigen of Erysipelothrix rhusiopathiae. Epid Infect 107: 637-649.
3. Sato H,, Y. Yamazaki, K. Tsuchiya, T. Aoyama, N. Akaba, T. Suzuki, A. Yokoyama, H. Saito, and N, Maehara. 1998. Use of the protective antigen of Erysipelothrix rhusiopathiae in the enzyme-linked immunosorbent assay and latex agglutination. Zentralbl Veterinarmed [B] 45(7):407-20.