Éditeur(s) : Inter-Research
Résumé : The pathogenicity of Vibrio penaeicida Strains KH-1 and AM101, their culture-free supernatant (CFS), and their protein fraction obtained by 40% of ammonium sulfate precipitation (PFs40) were assessed in experimental challenges against juvenile Litopenaeus vannamei. Live Vibrio cells, CFS, and PFs40 from the AM101 strain produced a significantly higher mortality (p < 0.05) compared to the KH-1 strain. Toxicity and median lethal doses (LD50) of Fast Protein Liquid Chromatography (FPLC) products were evaluated on L. vannamei. The first FPLC fraction sample (A) from PFs40 of the AM101 strain displayed LD50 values of 1.68 and 5.61 mu g protein ind.(-1), respectively. The second FPLC process from Fraction A showed a peak (A1) also with toxic effects to shrimp. PFs40, Fraction A, and Peak At showed a 38.5 kDa molecular band (SDS-PAGE), with activity on a gelatin protease zymogram. The lethal effect of PFs40 and Fraction A was inhibited by Proteinase K, CuCl2, E-64, and heat (60 and 100 degrees C) treatments, but was not inhibited by EDTA-Na-2, aprotinin, and soy trypsin treatments. These results and the zymogram inhibition test suggest the presence of a cysteine protease-like proteinaceous exotoxin as a dominant protease, secreted by V. penaeicida Strain AM101.
Diseases of aquatic organisms (0177-5103) (Inter-Research), 2005-11 , Vol. 67 , N. 3 , P. 201-207

Droits : Inter-Research 2005
http://archimer.ifremer.fr/doc/2005/publication-3618.pdf
DOI:10.3354/dao067201
http://archimer.ifremer.fr/doc/00000/3618/

Éditeur(s) : Universidad Autonoma de Baja California
Résumé : The pathogenicity of two V. penaeicida strains, AM101 and KH-1, with different geographic origin, and V. nigripulchritudo strain AM102, were investigated in juvenile blue shrimp species Litopenaeus stylirostris. Alive bacteria and protein fractions (PFs) obtained from cell-free supernatants (CFS) were used in experimental challenges. Strains AM102, AM101, and KH-1 produced respectively 60, 54 and 12% mortality at 96h after infection using 104 cfu mL-1 of bacterial suspension. Exocellular toxin-like factors were evidenced in CFS from the New Caledonian strains (AM102 and AM101) but not the Japanese strain (KH-1). At 48h post injection of each CFS, mortality rates were respectively 96,98 and 5% when these strains were cultivated at 20°C, whereas only O,16 and 5% mortality rates were observed when these strains were cultivated at 30°C. Clear differences in pathogenicity between both V. penaeicida strains of distinct geographic origin (AM101 and KH-1) were thus emphasized. Protein fractions were obtained from CFS of all the strains tested in this study and cultivated at 20°C, by ammonium sulphate precipitation. Whatever the used strain, significantly higher mortalities were produced with PFs obtained with 0-40% of ammonium sulphate saturation, in respect to those produced with PFs60 and PFs80. Shrimp injected with PFs40 from strains AM102, AM101 and KH-1, and at a 20-µg org-1 dose produced respectively 100, 90 and 60% mortality 46h after the challenge. The strain AM101 showed a mediam lethal dose of approximately 5µg protein org-1 (1-1.25 µg protein g-1 body weight) 59h after injection. The PFs40 from New Caledonian strains were fond sensitive to heating and proteinase K treatments, reinforcing thus the hypothesis of their proteinaceous nature. Surprisingly, PFs40 from each bacterial strain displayed similar protein bands by SDS-PAGE suggesting that the tested strains share a common exotoxic compound regardless their distinct geographic origin or species.
Ciencias Marinas (Universidad Autonoma de Baja California), 2003 , Vol. 29 , N. 1 , P. 77-88

Droits : Universidad Autonoma de Baja California
http://archimer.ifremer.fr/doc/2003/publication-2807.pdf
http://archimer.ifremer.fr/doc/00000/2807/