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 different degrees of virulence for mice and turbot (Scophthalmus maximus) has been evaluated in artificial and natural iron-restricted environments. All strains were capable of utilizing haemoglobin (Hb) and ferric ammonium citrate (FAC) as the sole iron sources in vitro. However, only virulent V. damsela strains were able to resist the bacteriostatic and bactericidal effects of human and turbot sera, their growth being enhanced 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-overloaded animals. The iron-treatment before the infection resulted in a significant reduction in the LD(50) of virulent strains. This fact demonstrates a positive correlation between iron availability in host fluids and degree of virulence in the species Vibrio damsela.