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Diagnostic tools for rapid detection and quantification of W eissella ceti NC 36 infections in rainbow trout
Author(s) -
Snyder A.K.,
Hinshaw J.M.,
Welch T.J.
Publication year - 2015
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12365
Subject(s) - rainbow trout , biology , pathogen , outbreak , trout , microbiology and biotechnology , fishery , virology , fish <actinopterygii>
Abstract Weissellosis of rainbow trout is caused by the Gram‐positive bacteria W eissella ceti and has been reported in C hina, B razil and the U nited S tates. This disease can result in high mortality in market‐sized fish and thus can cause significant economic loss. Thus far, phenotypic characterization and 16 S r RNA sequencing have been used to confirm a W eissellosis diagnosis. Here, we present the development of PCR ‐based diagnostic tools for the rapid identification and quantification of W . ceti within bacteriological culture and infected tissues. A duplex PCR , which amplifies both genus‐ and strain‐specific targets, positively identifies isolates as W . ceti NC 36. A q PCR assay was also developed to quantify pathogen load from infected tissues, using a W . ceti NC 36 unique locus. A proof of concept study was performed to demonstrate that quantification using traditional plate count methods and q PCR were significantly correlated when assessed from infected brain and spleen tissue. These tools were also used to confirm diagnosis of Weissellosis in a commercial rainbow trout farm during an outbreak investigation. These are the first diagnostic tools developed for identification and quantification of W . ceti infection within rainbow trout, contributing to rapid Weissellosis diagnosis, enhanced pathogen surveillance and epidemiological studies. Significance and Impact of the Study Weissellosis is a rapidly emerging infectious disease of farmed rainbow trout caused by W eissella ceti, a G ram‐positive lactic‐acid bacterium. This disease can cause significant economic loss, and thus, efforts to limit its spread are urgently needed and are dependent on the development of diagnostic tools. The article presents the development of PCR ‐based diagnostic assays for the rapid identification of W . ceti and for quantification of pathogen load directly from tissues without the need for bacterial amplification or isolation. These tools are critical for rapid confirmation of W eissellosis diagnosis and for studying the epidemiology of this emerging pathogen.