ANTIGENIC AND MOLECULAR CHARACTERIZATION OF YERSINIA-RUCKERI PROPOSALFOR A NEW INTRASPECIES CLASSIFICATION

The serological and molecular properties of a group of 17 Yersinia ruc keri strains isolated from cultured rainbow trout in Spain were compar ed with a total of 36 collection strains isolated from fish in other g eographic areas. The serological relationship among isolates, as well as the study of their antigenic determinants (LPS and membrane protein s) allow to propose a new serotyping scheme with four O-serotypes (fro m O1 to O4). Moreover, serotypes O1 and O2 mere divided in two and thr ee groups respectively based mainly on minor differences observed in L PS and membrane protein profiles. The patterns obtained in the analysi s of the LPS and proteins present in the extracellular products also s upport the serological scheme proposed. The strains showed a great gen etic homogeneity, displaying similar DNA fingerprint patterns regardle ss of their serotype. In contrast, only the serotype O1 isolates harbo ur a plasmid of about 50 MDa, while the strains of the other serotypes presented no extrachromosomical DNA or only small plasmids (less than 10 MDa).