Sea lice, Lepeophtheirus salmonis (Krøyer 1837), infected Atlantic salmon (Salmo salar L.) are more susceptible to infectious salmon anemia virus

Overview
TitleSea lice, Lepeophtheirus salmonis (Krøyer 1837), infected Atlantic salmon (Salmo salar L.) are more susceptible to infectious salmon anemia virus
AuthorsBarker SE, Bricknell IR, Covello J, Purcell S, Fast MD, Wolters W, Bouchard DA
TypeJournal Article
Journal NamePloS one
Volume14
Issue1
Year2019
Page(s)e0209178
CitationBarker SE, Bricknell IR, Covello J, Purcell S, Fast MD, Wolters W, Bouchard DA. Sea lice, Lepeophtheirus salmonis (Krøyer 1837), infected Atlantic salmon (Salmo salar L.) are more susceptible to infectious salmon anemia virus. PloS one. 2019; 14(1):e0209178.

Abstract

The role of parasitic sea lice (Siphonostomatoida; Caligidae), especially Lepeophtheirus salmonis, in the epidemiology of Infectious Salmon Anemia Virus (ISAv) has long been suspected. The epidemiological studies conducted during the 1998 major Infectious Salmon Anaemia (ISA) outbreak in Scotland demonstrated a strong correlation between sea lice presence and ISAv positive sites or subsequent clinical outbreaks of ISA. The question posed from this observation was "do sea lice infestations on Atlantic salmon make them more susceptible to viral infections?" This study investigated the role that sea lice infestations have on the severity of ISAv infections and disease mortality in experimental populations of farmed Atlantic salmon (Salmo salar). A series of experiments was carried out that investigated the potential of sea lice to modify the outcome of an ISAv infection. Experimental populations of Atlantic salmon were established that had: no lice and no ISAv, a single infection with either ISAv or lice and a co-infection with lice then ISAV. The results were quite clear, the process of infestation by the parasite prior to ISAv exposure significantly increased the mortality and death rates of Atlantic salmon, when compared to uninfected controls and ISAv infected groups only. This was consistent over two source strains of Atlantic salmon (Pennobscot and Saint John River), but the severity and timing was altered. Immunological responses were also consistent in that pro-inflammatory genes were induced in lice only and co-infected fish, whereas the anti-viral response, Mx, MH class I β, Galectin 9 and TRIM 16, 25 genes were down-regulated by lice infection prior to and shortly after co-infection with ISAv. It is concluded that the sea lice settlement on Atlantic salmon and the parasite's subsequent manipulation of the host's immune system, which increases parasite settlement success, also increased susceptibility to ISAv.

Author Details
Additional information about authors:
Details
1Sarah E Barker
2Ian R Bricknell
3Julia Covello
4Sarah Purcell
5Mark D Fast
6William Wolters
7Deborah A Bouchard
Properties
Additional details for this publication include:
Property NameValue
Journal CountryUnited States
Publication TypeJournal Article
Language Abbreng
LanguageEnglish
Elocation10.1371/journal.pone.0209178
DOI10.1371/journal.pone.0209178
Journal AbbreviationPLoS ONE
Publication Date2019
eISSN1932-6203
ISSN1932-6203
Publication ModelElectronic-eCollection
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PMID: PMID:30650077