Antigenic profile and protective role of a 37 kDa major outer membrane protein of Edwardsiella tarda

A 37 kDa major outer membrane protein (MOMP) was purified from the outer me mbrane fraction of Edwardsiella tarda EF-1 strain. The protein had a glycop rotein profile and showed immunogenicity to Japanese eel Anguilla japonica. Immunoblot analysis by using an eel antiserum raised against this MOMP rev ealed no antigenic cross-reaction with other MOMPs of this bacterium. Eel a ntisera against 37 kDa MOMP extracted from EF-1 and V1 strains showed cross agglutination to formalin-killed cells and heated cells between the two st rains. The results indicate that the heat-resistant antigen, 37 kDa, MOMP i s located on the cell surface and has a common antigenic determinant. immun ization with the purified 37 kDa MOMP of EF-1 and V1 strains increased resi stance in eel against challenge by intraperitoneal injection with live EF-1 strain. The results show that this 37 kDa MOMP is one of the protective an tigens of E. tarda. As the MOMP was found in two strains of different serot ypes, it is probably contributed as a promising vaccine antigen against edw ardsiellosis caused by E. tarda.