Identification and genetic characterization of Piscirickettsia salmonis in native fish from southern Chile

Abstract

Piscirickettsia salmonis is the etiological agent of piscirickettsiosis, a severe disease causing high mortalities in salmonids. This bacterium has been previously identified and isolated in all cultivated salmonids in Chile and worldwide, including Salmo salar, Oncorhynchus kisutch, and O. mykiss, in addition to being found in non-salmonid species such as Dicentrarchus labrax and Atractoscion nobilis. In this study, the 16S rRNA gene and intergenic spacer ITS-1 of P. salmonis were amplified by PCR from DNA samples extracted from the native Chilean fish species Eleginops maclovinus, Odontesthes regia, Sebastes capensis, and Salilota australis. Analysis of the 16S rRNA sequences from O. regia demonstrated a close phylogenetic relationship with the 16S rRNA gene in the Chilean EM-90 strain. The 16S rRNA sequences from E. maclovinus, S. capensis, and S. australis were related to the Chilean LF-89 sequence and Scottish strains. To confirm these findings, analysis of P. salmonis ITS-1 sequences obtained from the 4 sampled native species demonstrated a high degree of identity and a close phylogenetic relationship with Chilean P. salmonis sequences, including LF-89 and EM-90. These results suggest a strong relationship between the nucleotide sequences from the 16S rRNA and ITS-1 genes amplified from native fish with those sequences described in the first P. salmonis strains to be identified and isolated in Chile.KEY WORDS: 16S gene · ITS-1 · rDNA sequences · Piscirickettsiosis · Native fish · SalmonidsResale or republication not permitted without written consent of the publisher

Addressing viral and bacterial threats to salmon farming in Chile: historical contexts and perspectives for management and control

“…In this context, Contreras‐Lynch et al . () describe the identification of P. salmonis in native fish from southern Chile, and the analysis of the amplified 16S ribosomal gene revealed sequences phylogenetically related to the 16S rDNA of the genotype LF89 and EM90 of the bacterium.…”

Piscirickettsia salmonis infection in cultured lumpfish (Cyclopterus lumpus L.)

“…Piscirickettsiosis occurs in farmed Atlantic salmon in Ireland, and P. salmonis has been detected in a range of wild fish species (Contreras‐Lynch et al . ). The reservoir of the infection could therefore have been other fish species present in the vicinity of the water inlet.…”

“…The bacterium has also been detected from a number of wild marine fish species off the coast of Chile (Contreras‐Lynch et al . ).…”

Intermediary metabolic response and gene transcription modulation on the Sub‐Antarctic notothenioid Eleginops maclovinus (Valenciennes, 1930) injected with two strains of Piscirickettsia salmonis

“…The physiological changes associated with P. salmonis infection not only represents an important problem to salmon species utilized in the Chilean aquaculture, but also to other fish species living in close proximity to sea cages. For instance, P. salmonis has been previously isolated and described from native Chilean fish, including Cape redfish ( Sebastes capensis ), Chilean silverside ( Odonthestes regia ), Pacific sandperch ( Prolatilus jugularis ), Inanga ( Galaxias maculatus ) and Patagonian blennie ( Eleginops maclovinus ; Contreras‐Lynch et al, ; Fortt, Cabello, & Buschmann, ). The latter, E. maclovinus , is a species of great economic importance in the artisanal and recreational fisheries, particularly in marine and estuarine areas where large numbers of these fish congregate near salmon sea cages.…”