ROLE OF IRON IN THE PATHOGENICITY OF VIBRIO-DAMSELA FOR FISH AND MAMMALS

The ability to obtain iron of 14 isolates of Vibrio damsela with diffe rent degrees of virulence for mice and turbot (Scophthalmus maximus) h as been evaluated in artificial and natural iron-restricted environmen ts. All strains were capable of utilizing haemoglobin (Hb) and ferric ammonium citrate (FAC) as the sole iron sources in vitro. However, onl y virulent V. damsela strains were able to resist the bacteriostatic a nd bactericidal effects of human and turbot sera, their growth being e nhanced by the addition of Hb and FAC. The inhibitory effect of these sera an the growth of the non-pathogenic strain (ATCC 35083), however, was reversed by heat treatment (56 degrees C for 60 min). The role of iron-availability on the virulence was investigated in iron-overloade d animals. The iron-treatment before the infection resulted in a signi ficant reduction in the LD(50) of virulent strains. This fact demonstr ates a positive correlation between iron availability in host fluids a nd degree of virulence in the species Vibrio damsela.