Antigenic and cross-protection studies of biotype 1 and biotype 2 isolates ofYersinia ruckeri in rainbow trout, Oncorhynchus mykiss (Walbaum)

摘要

Aims: The study investigated antigen characteristics of biotype (bt) 1 and bt 2isolates of Yersinia ruckeri.Methods and Results: The cell surface characteristics of Y. ruckeri werecompared for their antigenic characteristics using polyclonal antibodies thatrevealed that both biotypes had a homogenous whole-cell protein antigenicprofile. Notable differences in the antigenic properties were observed in thelipopolysaccharide profile of both biotypes. Two iron-regulated outer membraneproteins (IROMP) of c. 90 and 100 kDa were shown to be major specific antigens.The results demonstrate for the first time differences in antigens between bt 1and bt 2 isolates of serotype O1 isolates of Y. ruckeri. The protection inducedin rainbow trout by a commercial monovalent, and bivalent inactivated vaccinewas tested with the outcome that the ability of isolates to cause mortality invaccinated fish varied with geographical location. In this context, vaccinationstudies suggested that the O antigen was the dominant immunogenic moleculeinvolved in protection against the disease.Conclusions: The O antigen of Y. ruckeri was the dominant immunogenic moleculeinvolved in the protection of rainbow trout against enteric redmouth disease.Significance and Impact of the Study: There are distinct phenotypic andantigenic differences in Y. ruckeri bt 1 and bt 2 with O antigen recognized asthe dominant immunogenic molecule. The data have significance in explaining thelack of success of the earlier monovalent vaccine and demonstrate theeffectiveness of the newer bivalent vaccine.