Characterization of Vibrio anguillarum strains isolated from diseased fish in Finland

Characterization of V. anguillarum strains (n = 109) isolated from diseased salmonids was performed. Eight O serovars were found among the strains. Serovar O1 was predominant (90%), while serovars O2, O3, O5, O8, O9, and a new serovar Va NT2, were represented by 1 or 2 strains. Two strains remained non-typeable. One of these was cross-reactive with several antisera, but had a LPS profile identical to that of serovar O8. All serovars showed specific LPS profiles. All but 1 of the O1 strains had a plasmid comparable in size to the pJM1 virulence plasmid, while plasmids of different sizes were found in O2, Va NT2 and the non-typeable strains. Apart from a single strain resistant to tetracycline, all the strains were sensitive to oxolinic acid, tetracycline, and trimethoprim-sulfonamides. By their biochemical and antigenic properties strains causing vibriosis among salmonids in Finland closely resemble Scandinavian strains. Predominance of the serovars O1 and O2 suggests that commercial vaccines containing these serovars should afford sufficient protection against vibriosis in Finland.