Innate antiviral-like immune responses differ among divergent European and North American farmed and wild Atlantic salmon (Salmo salar) and their hybrids

• Main Author: Dove, Sindy
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2022
• Subjects: Atlantic salmon; Newfoundland; Salmo salar
• Online Access: https://research.library.mun.ca/15720/; https://research.library.mun.ca/15720/3/converted.pdf

This thesis involved a study of the effect of North American (NA) farmed, European origin (EO) farmed, wild, and related hybrid cross types on the innate antiviral-like immune response in Atlantic salmon (Salmo salar). Since the 1970s, millions of farmed salmon have escaped causing concern about how interbreeding with wild salmon may affect wild populations. Farmed and wild salmon differ genetically, yet the immune responses of farmed-wild hybrids are not well understood. In Newfoundland, permission has been granted to start farming an EO strain in addition to the current NA strain from the Saint John River. As these strains differ genetically and geographically, there is concern about potential differences in immune responses. Hence, I used real-time quantitative polymerase chain reaction (qPCR) with head kidney templates to measure expression of seventeen antiviral and other immune-relevant biomarker genes (i.e., dhx58, gig1a, helz2, ifna, ifng, irf1a, irf7b, isg15a, mxb, pgds, rsad2a, rsad2b, stat1a, stat1c, tlr3, tlr7, and 5loxb) to assess the innate antiviral-like immune responses [i.e. to intraperitoneal (IP) injection with polyriboinosinic polyribocytidylic (pIC)] of six different Atlantic salmon cross types including pure crosses (i.e. NA, EO, and local Northeast Placentia River Wild) and three related hybrid crosses. Cross type abbreviations are as follows: pure Wild; pure European farmed (Farm.EO); pure North American farmed (Farm.NA); wild female crossed with Farm.EO male (Hyb.EO w♀); Farm.EO female crossed with wild male (Hyb.EO F♀); and Farm.NA female crossed with wild male (Hyb.NA F♀). At a basal transcript expression level, only one gene (pgds) showed significant cross type differences, where Hyb.NA F♀ had significantly higher expression than the Wild and Hyb.EO F♀. After pIC injection, fifteen of the seventeen target genes (i.e. all except pgds and 5loxb) were significantly upregulated. In addition, there were significant cross type differences in transcript expression of ifna, isg15a, rsad2a, ...