CLONAL ANALYSIS OF YERSINIA-RUCKERI BASED ON BIOTYPES, SEROTYPES AND OUTER-MEMBRANE PROTEIN-TYPES

The biotypes, serotypes and outer membrane protein-types (OMP-types) of 135 isolates of Yersinia ruckeri were analysed in an attempt to identify clonal groups and to examine in further detail the relationships between isolates from wide geographic areas. Each isolate could be assigned to one of two biotypes (1 and 2), one of five 0-serotypes (01, 02, 05, 06 and 07), and one of five OMP-types (1-5). Outer membrane protein analysis was able to differentiate between isolates within a given serotype. Thus, serotype 01 isolates consisted of OMP-types 1, 2, 3 and 4, serotype 02, 05 and 06 isolates consisted of OMP-types 1 and 2, and serotype 07 isolates consisted of OMP-types 1 and 5. Whereas OMP-types 3 and 4 were associated only with serotype 01, and OMP-type 5 was associated only with serotype 07, OMP-types 1 and 2 were associated with serotypes 01, 02, 05, 06 and 07, and 01, 02, 05 and 06, respectively. When biotype was taken into consideration, serotype 01 isolates of OMP-types 1 and 2 could be sub-divided into four groups; serotype 01 isolates could thus be sub-divided into six clonal groups. Two of these clonal groups were responsible for the majority of the disease outbreaks in Europe and represented 79% of the European isolates. A combination of biotype, serotype and OMP-type analysis was demonstrated to be useful in epidemiological studies of Y. ruckeri.