Immune response modulation upon sequential heterogeneous co-infection with Tetracapsuloides bryosalmonae and VHSV in brown trout (Salmo trutta)

Bartolomeo Gorgoglione*, Nick G.H. Taylor, Jason W. Holland, Stephen W. Feist, Christopher J. Secombes* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Simultaneous and sequential infections often occur in wild and farming environments. Despite growing awareness, co-infection studies are still very limited, mainly to a few well-established human models. European salmonids are susceptible to both Proliferative Kidney Disease (PKD), an endemic emergent disease caused by the myxozoan parasite Tetracapsuloides bryosalmonae, and Viral Haemorrhagic Septicaemia (VHS), an OIE notifiable listed disease caused by the Piscine Novirhabdovirus. No information is available as to how their immune system reacts when interacting with heterogeneous infections. A chronic (PKD) + acute (VHS) sequential co-infection model was established to assess if the responses elicited in co-infected fish are modulated, when compared to fish with single infections. Macro- and microscopic lesions were assessed after the challenge, and infection status confirmed by RT-qPCR analysis, enabling the identification of singly-infected and co-infected fish. A typical histophlogosis associated with histozoic extrasporogonic T. bryosalmonae was detected together with acute inflammation, haemorrhaging and necrosis due to the viral infection. The host immune response was measured in terms of key marker genes expression in kidney tissues. During T. bryosalmonae/VHSV-Ia co-infection, modulation of pro-inflammatory and antimicrobial peptide genes was strongly influenced by the viral infection, with a protracted inflammatory status, perhaps representing a negative side effect in these fish. Earlier activation of the cellular and humoral responses was detected in co-infected fish, with a more pronounced upregulation of Th1 and antiviral marker genes. These results reveal that some brown trout immune responses are enhanced or prolonged during PKD/VHS co-infection, relative to single infection.

Original languageEnglish
Pages (from-to)375-390
Number of pages16
JournalFish and Shellfish Immunology
Early online date21 Feb 2019
Publication statusPublished - May 2019

Bibliographical note

This work was supported by DEFRA [grant number F1198] in a joint project between SFIRC in Aberdeen, Scotland and CEFAS laboratory in Weymouth, England. Further funding to present this work at international conferences was granted to BG by European Association of Fish Pathologists (EAFP), British Society for Immunology (BSI), Fisheries Society of the British Isles (FSBI), European Society of Veterinary Virology (ESVV), and Aberdeen University Principal’s Excellence Fund. JWH was supported by the BBSRC (BB/K009125/1).


  • Antimicrobial Peptides
  • Co-infections
  • Fish immunology
  • Histopathology
  • Host-pathogen interaction
  • Immune response
  • Interferon
  • Myxozoa
  • Piscine Novirhabdovirus
  • Proliferative kidney disease
  • Response to pathogens
  • Salmonids
  • Th subsets


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