Virulence of Flavobacterium branchiophilum in experimentally infected salmonids

Abstract

The ability of selected strains of Flavobacterium branchiophilum to attach to and colonize the gills of five species of teleosts (four salmonid and one cyprinid) and cause mortality was investigated. In virulence studies with F. branchiophilum strain LAB4a, cumulative mortality was dose-dependent in rainbow trout, Oncorhynchus mykiss (Walbaum), and ranged from 0 to 75%. However, regardless of dose, the relative amount of gill-associated F. branchiophilum antigen inereased lh after challenge. The gill-associated F. branchiophilum antigen in fish which survived (moribund fish) increased by four to six times compared to that detected on the gills lh after challenge. The gill-associated antigen on moribund fish was not significantly different from that on the gills of dead fish. Flavobacterium branchiophilum strain LAB4a also attached to the gills of brook trout, Salvelinus fontinalis (Mitchell), rainbow trout, chinook salmon, Oncorhynchus tshawytscha (Walbaum), Arctic charr, Salvehnus alpinus (L.), and common shiners, Luxilus cornutus (Mitchell), following a 1-h bath exposure, and caused mortality in all species. The virulence of eight strains of F. branchiophilum for rainbow trout was examined. Both virulent and avirulent strains adhered to the gills following bath exposure (fimbriae were observed on all strains), but only virulent strains had the capacity to further colonize the gills and cause mortality.

Flavobacterium spartansii induces pathological changes and mortality in experimentally challenged Chinook salmon Oncorhynchus tshawytscha (Walbaum)

“…Indeed, the gill pathology observed in this study is also similar to what is reported in fish suffering from bacterial gill disease, caused by F. branchiophilum (Wakabayashi, Huh & Kimura 1989). For example, pale and swollen gills due to a proliferative hyperplasia of the gill epithelium that results in fusion of neighbouring lamellae is hallmark of infections associated with F. branchiophilum (Bullock 1990;Ostland et al 1995).…”

“…For example, pale and swollen gills due to a proliferative hyperplasia of the gill epithelium that results in fusion of neighbouring lamellae is hallmark of infections associated with F. branchiophilum (Bullock ; Ostland et al . ).…”

Experimental induction of gill disease in Atlantic salmon Salmo salar smolts with Tenacibaculum maritimum

“…Bacterial diseases of freshwater fish epithelia have been extensively studied with the primary focus upon bacteria from the Cytophagales, such as bacterial gill disease caused by Flavobacterium branchiophilum (Ostland et al 1994(Ostland et al , 1995, and necrotizing skin diseases such as columnaris disease caused by F. columnare (Thomas-Jinu & Goodwin 2004) and bacterial cold-water disease caused by F. psychrophilum (Cipriano et al 1996 and review by Nematollahi et al 2003). However, in marine fishes relatively few bacterial skin and gill diseases have been characterised.…”

Effects of hydrogen peroxide on clearance of formalin‐killed Flavobacterium branchiophilum from the gills of rainbow trout, Oncorhynchus mykiss (Walbaum)

“…Gill tissues were thawed and processed and 96well plates were coated with soluble gill antigen, as described by Ostland et al (1995). The GAFBA was estimated with an elisa, as previously described (MacPhee, .…”