PHENOTYPIC CHARACTERIZATION OF VIBRIO-VULNIFICUS BIOTYPE-2, A LIPOPOLYSACCHARIDE-BASED HOMOGENEOUS-O SEROGROUP WITHIN VIBRIO-VULNIFICUS

In this study, we have reevaluated the taxonomic position of biotype 2 of Vibrio vulnificus. For this purpose, we have biochemically and ser ologically characterized 83 biotype 2 strains from diseased eels, comp aring them with 17 biotype 1 strains from different sources, Selected strains were also molecularly analyzed and tested for eel and mouse pa thogenicity, Results have shown that biotype 2 (i) is biochemically ho mogeneous, indole production being the main trait that distinguishes i t from biotype 1, (ii) presents small variations in DNA restriction pr ofiles and outer membrane protein patterns, some proteins being immuno logically related to outer membrane proteins from biotype 1, (iii) exp resses a common lipopolysaccharide (LPS) profile, which is immunologic ally identical among strains and distinct from that of LPS of tested b iotype 1 strains, and (iv) contains at least two high-M(r) plasmids, R egarding host range, we have confirmed that both biotypes are pathogen ic for mice but only biotype 2 is pathogenic for eels. On the basis of these data, we propose that biotype 2 of V. vulnificus constitutes an LPS-based O serogroup which is phenotypically homogeneous and pathoge nic for eels, In this article, the serogroup is designated serogroup E (for eels).