Host specificity and clade dependent distribution of putative virulence genes in Moritella viscosa

• DOI: 10.1016/j.micpath.2014.09.014
• Publication Date: 2014-09-30T04:58:01Z
• Authors: Christian Karlsen; Anette Bauer Elli...; Christer Wiik-Nie...; Hanne C. Winther-...; Duncan J. Colquhoun; Henning Sørum
• Keywords: Hemolysin

Moritella viscosa is the aetiological agent of winter-ulcer disease in farmed salmonids North Atlantic. Previously, two major (typical and variant) genetic clades have been demonstrated within this bacterial species, one which almost solely related to Atlantic salmon (Salmo salar). In present study infection trials that 'typical' M. isolated from Norwegian was highly virulent fish species but resulted lower levels mortality rainbow trout. 'Variant' trout modest both To investigate possible background for inter-strain virulence differences, 38 isolates diverse geographical origin host a number other spp. were investigated presence/absence putative homologs. All positive DNA sequences coding for; Type VI secretion ATPase (clpV), hemolysin co-regulated protein (hcp), bacterioferritins (bfrA bfrB), lectin (hemG), phospholipase D (pld), multifunctional autoprocessing repeats-in-toxin (martxA), aerolysin (aer), invasin (inv), cytotoxic necrotizing factor (cnf), with exception isolate cnf could not be confirmed. The product an ABC transporter metal-binding lipoprotein (mat) consistently detected although 11 isolates, all phylogenetically related, appear produce truncated version. A insecticidal toxin complex (mitABC) exclusively our data indicate genes expressed co-transcribed. Transmission electron microscopy investigation revealed pili flagella surface structures on nine representing typical variant isolates. Our results provide strong support existence specificity/high salmon. gene distribution also provides further division viscosa, constitutes basis importance mitABC pathogenesis.