Changes in the interbranchial lymphoid tissue of Atlantic salmon (Salmo salar) affected by amoebic gill disease

Santos, Catarina Norte dos; Adams, Mark B.; Leef, MJ; Nowak, Barbara F.

doi:10.1016/j.fsi.2014.10.003

Cited by 14 publications

(4 citation statements)

References 37 publications

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“…Dalum and colleagues redefined the interbranchial lymphoid tissue as divided into a proximal part (pILT) in the interbranchial septum and a distal part (dILT) extending along the trailing edges of the filament [ 68 , 69 ], the same areas in which we found the inclusions. Modifications of the normal structure of the ILT has been shown in gill disorders caused by amoebic gill disease (AGD) in Atlantic salmon ( Salmo salar ) [ 70 ]. Since this disease is also characterised by epithelial hyperplasia [ 71 , 72 ], it has been suggested that migration of immune cells from the lymphoid organ and epithelial proliferation triggered by the pathogen might be factors contributing to the reshaping of the tissue during infection [ 70 ].…”

Section: Discussionmentioning

confidence: 99%

“…Modifications of the normal structure of the ILT has been shown in gill disorders caused by amoebic gill disease (AGD) in Atlantic salmon ( Salmo salar ) [ 70 ]. Since this disease is also characterised by epithelial hyperplasia [ 71 , 72 ], it has been suggested that migration of immune cells from the lymphoid organ and epithelial proliferation triggered by the pathogen might be factors contributing to the reshaping of the tissue during infection [ 70 ]. Future study should characterize the ILT in healthy greater amberjack and investigate the reasons leading to what seems to be a lack of immune response following mucocyte infections in these areas.…”

Section: Discussionmentioning

confidence: 99%

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Epitheliocystis in Greater Amberjack: Evidence of a Novel Causative Agent, Pathology, Immune Response and Epidemiological Findings

Cascarano

Ruetten²,

Vaughan³

et al. 2022

Microorganisms

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Epitheliocystis is a fish gill disease caused by a broad range of intracellular bacteria infecting freshwater and marine fish worldwide. Here we report the occurrence and progression of epitheliocystis in greater amberjack reared in Crete (Greece). The disease appears to be caused mainly by a novel Betaproteobacteria belonging to the Candidatus Ichthyocystis genus with a second agent genetically similar to Ca. Parilichlamydia carangidicola coinfecting the gills in some cases. After a first detection of the disease in 2017, we investigated epitheliocystis in the following year’s cohort of greater amberjack juveniles (cohort 2018) transferred from inland tanks to the same cage farm in the open sea where the first outbreak was detected. This cohort was monitored for over a year together with stocks of gilthead seabream and meagre co-farmed in the same area. Our observations showed that epitheliocystis could be detected in greater amberjack gills as early as a month following the transfer to sea cages, with ionocytes at the base of the gill lamellae being initially infected. Cyst formation appears to trigger a proliferative response, leading to the fusion of lamellae, impairment of gill functions and subsequently to mortality. Lesions are characterized by infiltration of immune cells, indicating activation of the innate immune response. At later stages of the outbreak, cysts were no longer found in ionocytes but were observed in mucocytes at the trailing edge of the filament. Whole cysts appeared finally to be expelled from infected mucocytes directly into the water, which might constitute a novel means of dispersion of the infectious agents. Molecular screening indicates that meagre is not affected by this disease and confirms the presence of previously described epitheliocystis agents, Ca. Ichthyocystis sparus, Ca. Ichthyocystis hellenicum and Ca. Similichlamydia spp., in gilthead seabream. Prevalence data show that the bacteria persist in both gilthead seabream and greater amberjack cohorts after first infection.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Epitheliocystis in Greater Amberjack: Evidence of a Novel Causative Agent, Pathology, Immune Response and Epidemiological Findings

Cascarano

Ruetten²,

Vaughan³

et al. 2022

Microorganisms

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“…This is consistent with previously published 28 day AGD cohabitation studies (Findlay et al . 1995 ; Zilberg and Munday, 2000 ) as well as bath challenge studies of the same duration (250 amoebae trophozoites L −1 ) (Norte dos Santos et al 2013 ) or shorter (10 days) with a higher amoebae load (2000 trophozoites L −1 ) (Pennacchi et al 2014 ). Additionally, non-significant differences in the levels of grossly observable pathology between groups for each time point indicate that the cohabitation challenge utilized provided a consistent approach to inducing AGD under experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

A comparison of disease susceptibility and innate immune response between diploid and triploid Atlantic salmon (Salmo salar) siblings following experimental infection with Neoparamoeba perurans, causative agent of amoebic gill disease

et al. 2017

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SUMMARYFew studies have focussed on the health and immunity of triploid Atlantic salmon and therefore much is still unknown about their response to commercially significant pathogens. This is important if triploid stocks are to be considered for full-scale commercial production. This study aimed to investigate and compare the response of triploid and diploid Atlantic salmon to an experimental challenge with Neoparamoeba perurans, causative agent of amoebic gill disease (AGD). This disease is economically significant for the aquaculture industry. The results indicated that ploidy had no significant effect on gross gill score or gill filaments affected, while infection and time had significant effects. Ploidy, infection and time did not affect complement or anti-protease activities. Ploidy had a significant effect on lysozyme activity at 21 days post-infection (while infection and time did not), although activity was within the ranges previously recorded for salmonids. Stock did not significantly affect any of the parameters measured. Based on the study results, it can be suggested that ploidy does not affect the manifestation or severity of AGD pathology or the serum innate immune response. Additionally, the serum immune response of diploid and triploid Atlantic salmon may not be significantly affected by amoebic gill disease.

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“…In a recent report in Atlantic salmon challenged with infectious salmon anemia virus, the size of the ILT decreased and levels of CD3ζ transcripts increased indicating that this structure plays a role in the antiviral immune response [ 15 ]. In the case of amoebic gill disease, salmon ILT seemed to increase in size in response to infection, however, the increase in size was explained by epithelial hyperplasia rather than expansion of the T cell populations in response to infection [ 68 ].…”

Section: Adaptive Mucosal Immune Responses Of Teleost Fishmentioning

confidence: 99%

The Mucosal Immune System of Teleost Fish

Salinas

2015

Biology

335

205

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Teleost fish possess an adaptive immune system associated with each of their mucosal body surfaces. Evidence obtained from mucosal vaccination and mucosal infection studies reveal that adaptive immune responses take place at the different mucosal surfaces of teleost. The main mucosa-associated lymphoid tissues (MALT) of teleosts are the gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), the gill-associated lymphoid tissue (GIALT) and the recently discovered nasopharynx-associated lymphoid tissue (NALT). Teleost MALT includes diffuse B cells and T cells with specific phenotypes different from their systemic counterparts that have co-evolved to defend the microbe-rich mucosal environment. Both B and T cells respond to mucosal infection or vaccination. Specific antibody responses can be measured in the gills, gut and skin mucosal secretions of teleost fish following mucosal infection or vaccination. Rainbow trout studies have shown that IgT antibodies and IgT+ B cells are the predominant B cell subset in all MALT and respond in a compartmentalized manner to mucosal infection. Our current knowledge on adaptive immunity in teleosts is limited compared to the mammalian literature. New research tools and in vivo models are currently being developed in order to help reveal the great intricacy of teleost mucosal adaptive immunity and help improve mucosal vaccination protocols for use in aquaculture.

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Changes in the interbranchial lymphoid tissue of Atlantic salmon (Salmo salar) affected by amoebic gill disease

Cited by 14 publications

References 37 publications

Epitheliocystis in Greater Amberjack: Evidence of a Novel Causative Agent, Pathology, Immune Response and Epidemiological Findings

Epitheliocystis in Greater Amberjack: Evidence of a Novel Causative Agent, Pathology, Immune Response and Epidemiological Findings

A comparison of disease susceptibility and innate immune response between diploid and triploid Atlantic salmon (Salmo salar) siblings following experimental infection with Neoparamoeba perurans, causative agent of amoebic gill disease

The Mucosal Immune System of Teleost Fish

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