Sigridur Gudmundsdottir - Academia.edu (original) (raw)

Papers by Sigridur Gudmundsdottir

Research paper thumbnail of Detection of Renibacterium salmoninarum in salmonid kidney samples: a comparison of results using double-sandwich ELISA and isolation on selective medium

Journal of Fish Diseases, May 1, 1993

A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L.... more A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L., brown trout, Salmo trutta L., Aretic charr. Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). were screened for Renibacterium salmoninarum using double-sandwich ELISA and bacterial isolation. For bacterial isolation, samples were homogenized, washed, plated onto S-KDM and incubated for 12 weeks. Samples for ELISA were kept frozen until tested. Alter thawing, 25% homogenates in PBS were heated at KIOT for 15 min in the presence (2 5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisole) and then centrifugcd. The supernatant was tested with polyclonal antibodies against whole bacterium in a double-sandwich ELISA. In seven out of 12 groups tested, all samples wore negative in both tests. Positive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in fouT out of these five groups. The ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.

Research paper thumbnail of Evaluation of cross protection by vaccines against atypical and typical furunculosis in Atlantic salmon, Salmo salar L

Journal of Fish Diseases, 1997

In Iceland, farmed salmonids are vaccinated against A. salmonicida ssp. achromogenes (Asa), which... more In Iceland, farmed salmonids are vaccinated against A. salmonicida ssp. achromogenes (Asa), which causes atypical furunculosis and is endemic in local waters. Classical furunculosis, caused by A. salmonicida ssp. salmonicida (Ass), was not diagnosed in this country until June 1995. In the present study, protection in experimental challenges against atypical and classical furunculosis in Atlantic salmon vaccinated with an autogenous Asa bacterin (Iceland Biojec.OO, IBOO), a commercial furunculosis vaccine (Biojec.1500), or a mixture of both vaccines was compared. The results showed that both vaccines gave protection against an injection challenge with Asa. However, better protection was obtained with the IBOO (homologous) vaccine. Infection of Asa by cohabitation could not be established in fresh water. Fish vaccinated with Biojec.1500 or with both vaccines simultaneously were equally well protected against Ass in a cohabitation challenge. On the other hand, no protection against cla...

Research paper thumbnail of Effects of bacterial treatment at early stages of Atlantic cod (Gadus morhuaL.) on larval survival and development

Journal of Applied Microbiology, 2010

Aims: To assess the effects of bacterial treatment at the earliest stages of cod rearing on the m... more Aims: To assess the effects of bacterial treatment at the earliest stages of cod rearing on the microbial load, larval development and performance, testing three bacterial strains (Carnobacterium divergens V41, Arthrobacter sp. and Enterococcus sp.) in vivo that were previously shown to have inhibitory potential towards fish pathogens in vitro. Methods and Results: A bacterial mixture was added eight times to the rearing water from the prehatch to the mid-larval stage (a 38-day period). Microbiological analysis of ova, larvae and rearing water was performed regularly. Larval performance and development were evaluated by survival rate, hypersalinity tolerance and physiological measurements. Different larval survival rates were observed within and between treatments, and possibly explained by variations in larval microflora and established probionts. Larvae from one silo, which had been bathed in the bacterial suspension, showed the highest survival rate (42AE1%), lowest Vibrio levels, and were significantly heavier (19AE3%) and more stress tolerant than control larvae (P < 0AE01). This coincided with the intestinal establishment of two of the tested bacteria. Conclusions: Arthrobacter and Enterococcus strains added regularly to the rearing water from the postfertilized egg stage can become established in larval gastrointestinal tract. The Enterococcus strain was associated with increased larval growth, performance and microflora control, indicating its probiotic nature. Significance and Impact of the Study: Regular application of autochthonous probionts may promote larval welfare, development and stress tolerance at early stages, hence increasing production yield in intensive cod larviculture.

Research paper thumbnail of Gadus morhua L: Acute phase responses in larvae and juveniles

Fish & Shellfish Immunology, 2013

Research paper thumbnail of Epidemiology of Renibacterium salmoninarum in Scotland and the potential for compartmentalised management of salmon and trout farming areas

Aquaculture, 2012

Bacterial kidney disease (BKD) (caused by Renibacterium salmoninarum) can result in significant m... more Bacterial kidney disease (BKD) (caused by Renibacterium salmoninarum) can result in significant mortality in Scottish salmon farms, but is considered to be a minor issue on trout farms. Controlling R. salmoninarum infection in trout to protect farmed salmon would be effective only if the risk posed from trout is significant both in absolute terms and relative to other potential sources of R. salmoninarum. To assess this, three complementary reviews are undertaken: review of data quality on BKD in Scotland and the national level prevalence and dynamics these data imply; case studies of recent BKD outbreaks in Scotland; and an assessment of the epidemiological and management factors that maintain and spread R. salmoninarum within and between the trout and salmon industries. These are then synthesised into a conclusion on the factors required for control of BKD in salmon. Most observed spread of R. salmoninarum occurred within single species or even companies, so the majority of cases in farmed salmon are linked to other salmon (and not to trout) farms. There is substantive geographical separation of areas of production for trout and salmon and transmission between salmon and trout networks is limited. The bacterium does not survive long in water so hydrodynamic transmission is likely to be localised. Currently R. salmoninarum is extremely rare in Scottish wild fish; this has not always been the case. Wild fish therefore probably play a limited role, but might act as reservoirs or vectors. The general conclusion is that to a large extent the transmission of R. salmoninarum in salmon and trout production can be separated and so there is potential to compartmentalise BKD controls, either by host species or geographical area.

Research paper thumbnail of Experimental challenges with Renibacterium salmoninarum in Arctic charr Salvelinus alpinus

Diseases of Aquatic Organisms, Mar 30, 2017

Arctic charr Salvelinus alpinus L. is an important species in Icelandic aquaculture and the most ... more Arctic charr Salvelinus alpinus L. is an important species in Icelandic aquaculture and the most common wild salmonid in Iceland. A study on the course of infection with the bacterium Renibacterium salmoninarum was conducted using 3 different challenge methods in brackish and fresh water. Bacterial isolation, ELISA and PCR tests were used for detection of the bacterium in multiple organ samples. In an experiment, run for 34 wk in brackish water, infection was established by intraperitoneal injection with 5 × 10 6 colony forming units (CFU) fish −1. There were external and internal symptoms of bacterial kidney disease (BKD) and mortalities between 6 and 13 wk after injection. A cohabitation trial was run simultaneously and infection was well established after 4 wk, as demonstrated by the detection methods applied. Symptoms of BKD were not seen and all but 1 cohabitant survived. In a separate experiment, infection was established by pumping a fixed amount of water from a tank with fingerlings infected by intraperitoneal injection into tanks with naïve fish, in fresh or brackish water, for 6 wk. Fish in the inflow tanks were reared for an additional 3 wk. There were neither macroscopic symptoms nor mortalities. ELISA and PCR tests showed that infection started to take hold after 3 wk. The challenge trials demonstrated that Arctic charr is susceptible to R. salmoninarum. Cohabitation and inflow of water from tanks with infected fish provide useful models for further studies on R. salmoninarum infection acquired in a natural way in Arctic charr.

Research paper thumbnail of Evaluation of a semi-nested PCR for detection of Renibacterium salmoninarum in samples from kidney, gill and ovarian fluid of Atlantic salmon broodfish

Icelandic Agricultural Sciences, 2013

A semi-nested PCR (snPCR) for detection of Renibacterium salmoninarum that causes bacterial kidne... more A semi-nested PCR (snPCR) for detection of Renibacterium salmoninarum that causes bacterial kidney disease (BKD) in salmonids was constructed. The efficacy of the snPCR was evaluated by comparison with nested PCR (nPCR) and two ELISA methods on kidney, ovarian fluid and gill samples collected from Atlantic salmon broodfish with escalating disease. The PCR methods using a conventional isolation kit identified equal numbers of positive samples, or 30%, with acceptable agreement. The ratio of positive kidney samples in PCR increased significantly, 42.5% in snPCR and 45% in nPCR, when an FTA minicard was used for DNA isolation. ELISA, using polyclonal antibodies, detected the highest number of positive samples (65%) and ELISA using monoclonal antibodies the lowest (17.5%). Ovarian fluid and gills gave inadequate results and cannot replace kidney samples for determination of R. salmoninarum infection in Atlantic salmon broodfish.

Research paper thumbnail of Extracellular vesicles, deiminated protein cargo and microRNAs are novel serum biomarkers for environmental rearing temperature in Atlantic cod (Gadus morhua L.)

Aquaculture Reports, 2020

The Open University's repository of research publications and other research outputs Extracellula... more The Open University's repository of research publications and other research outputs Extracellular vesicles, deiminated protein cargo and microRNAs are novel serum biomarkers for environmental rearing temperature in Atlantic cod (Gadus morhua L.)

Research paper thumbnail of Extracellular vesicles from cod (Gadus morhua L.) mucus contain innate immune factors and deiminated protein cargo

Developmental & Comparative Immunology, 2019

Extracellular vesicles are released from cells and participate in cell communication via transfer... more Extracellular vesicles are released from cells and participate in cell communication via transfer of protein and genetic cargo derived from the parent cells. EVs play roles in normal physiology and immunity and are also linked to various pathological processes. Peptidylarginine deiminases (PADs) are phylogenetically conserved enzymes with physiological and pathophysiological roles. PADs cause post-translational protein deimination, resulting in structural and, in some cases, functional changes in target proteins and are also linked to EV biogenesis. This study describes for the first time EVs isolated from cod mucosa. Mucosal EVs were characterised by electron microscopy, nanoparticle tracking analysis and EV-specific surface markers. Cod mucosal EVs were found to carry PAD, complement component C3 and C-reactive proteins. C3 was found to be deiminated in both whole mucus and mucosal EVs, with some differences, and further 6 deiminated immune and cytoskeletal proteins were identified in EVs by LC-MS/MS analysis. As mucosal surfaces of teleost fish reflect human mucosal surfaces, these findings may provide useful insights into roles of EVs in mucosal immunity throughout phylogeny. Highlights  Extracellular vesicles (EVs) are described for the first time in cod mucosa  EVs from cod mucosa contain complement component C3, CRP-I and CRP-II  Deiminated forms of complement component C3 are exported in cod mucosal EVs  Deiminated protein cargo of cod mucosal EVs includes cytoskeletal and immune proteins

Research paper thumbnail of Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny - Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.)

Developmental & Comparative Immunology, 2018

Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny... more Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny-Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.

Research paper thumbnail of Post-translational Protein Deimination in Cod (Gadus morhua L.) Ontogeny Novel Roles in Tissue Remodelling and Mucosal Immune Defences?

Developmental and comparative immunology, Jan 13, 2018

Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophys... more Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophysiological roles conserved throughout phylogeny. PADs promote post-translational deimination of protein arginine to citrulline, altering the structure and function of target proteins. Deiminated proteins were detected in the early developmental stages of cod from 11 days post fertilisation to 70 days post hatching. Deiminated proteins were present in mucosal surfaces and in liver, pancreas, spleen, gut, muscle, brain and eye during early cod larval development. Deiminated protein targets identified in skin mucosa included nuclear histones; cytoskeletal proteins such as tubulin and beta-actin; metabolic and immune related proteins such as galectin, mannan-binding lectin, toll-like receptor, kininogen, Beta2-microglobulin, aldehyde dehydrogenase, bloodthirsty and preproapolipoprotein A-I. Deiminated histone H3, a marker for anti-pathogenic neutrophil extracellular traps, was particularly el...

Research paper thumbnail of Rannsóknir eru undirstaða þróunar og hagsældar í landbúnaði

Rannsóknir og þróun eru undirstaða allra atvinnugreina. Atvinnugrein sem heldur ekki í við framfa... more Rannsóknir og þróun eru undirstaða allra atvinnugreina. Atvinnugrein sem heldur ekki í við framfarir og þróun þrífst ekki eða dafnar til lengdar. Á Tilraunastöð Háskóla Íslands í meinafraeði að Keldum eru stundaðar rannsóknir sem tengjast dýraheilbrigði og sjúkdómum í dýrum og mönnum. Þar er veitt ráðgjöf og þjónusta í þágu heilbrigðiseftirlits, sjúkdómagreininga og sjúkdóma­ varna fyrir búfé, eldisfiska og önnur dýr. Nemar í líffraeði, lífefnafraeði, lífeindafraeði og dýralaekningum vinna rannsóknarverkefni á fraeða­ sviðum stofnunarinnar sem hluta af grunn­ eða framhaldsnámi sínu. Með vaxandi innflutningi, hnatt­ vaeðingu og hlýnandi loftslagi má gera ráð fyrir að nýir smitsjúkdómar berist til landsins í auknum maeli. Fyrir utan haettulega smitsjúkdóma sem herja á búpening og geta valdið fjárhagslegu tjóni eru margir af varasömustu smit­ sjúkdómum í mönnum svokallaðar súnur (zoonosis), en það eru sýklar sem smitast úr dýrum í fólk (s.s. fuglaflensa, svínaflensa, ebólaveira og flei...

Research paper thumbnail of Survival and humoral antibody response of Atlantic salmon, Salmo salar L., vaccinated against Aeromonas salmonicida ssp. achromogenes

Journal of Fish Diseases, 1997

(Holt, Krieg, Sneath, Staley & Williams 1994): ssp. Atlantic salmon were vaccinated against A... more (Holt, Krieg, Sneath, Staley & Williams 1994): ssp. Atlantic salmon were vaccinated against Aeromonas salmonicida, ssp. achromogenes, ssp. masoucida and salmonicida ssp. achromogenes (Asa) by injection with ssp. smithia. The causative agent of furunculosis in three vaccines developed in our laboratory and an salmonid fish is A. salmonicida ssp. salmonicida, with autogenous bacterin (IcelandBiojec.OO, IBOO) the strains being referred to as typical. Strains of the produced by a commercial vaccine producer. The other subspecies are termed atypical. humoral antibody responses to bacterial antigens were In Iceland, atypical furunculosis caused by monitored by ELISA and Western blotting. The fish A. salmonicida ssp. achromogenes is an endemic disease were challenged by infection with Asa 6 and 12 weeks causing high mortality on fish farms using brackish post-vaccination. Protection was induced in all water for rearing salmonid fish and in captive cod of groups of vaccinated fish. The protection achieved wild origin cultivated in sea cages. Furthermore, the was time-dependent. The autogenous bacterin, susceptibility of halibut to the bacterium has been IBOO, induced a protective immune response later shown by experimental infection. The bacterium has than our experimental vaccines. All the vaccines tested been isolated from wild marine fish species and induced specific antibody response that increased clinical signs are frequently detected in infected wild between 6 and 12 weeks after vaccination. The salmonids. The disease is systemic and external signs antibody response was mainly directed against the A- are similar to furunculosis including haemorrhages layer protein, but antibodies to other bacterial and lesions (furuncles) in skin and muscle

Research paper thumbnail of Pentraxins CRP-I and CRP-II are post-translationally deiminated and differ in tissue specificity in cod (Gadus morhua L.) ontogeny

Developmental and comparative immunology, Jan 16, 2018

Pentraxins are fluid phase pattern recognition molecules that form an important part of the innat... more Pentraxins are fluid phase pattern recognition molecules that form an important part of the innate immune defence and are conserved between fish and human. In Atlantic cod (Gadus morhua L.), two pentraxin-like proteins have been described, CRP-I and CRP-II. Here we show for the first time that these two CRP forms are post-translationally deiminated (an irreversible conversion of arginine to citrulline) and differ with respect to tissue specific localisation in cod ontogeny from 3 to 84 days post hatching. While both forms are expressed in liver, albeit at temporally differing levels, CRP-I shows a strong association with nervous tissue while CRP-II is strongly associated to mucosal tissues of gut and skin. This indicates differing roles for the two pentraxin types in immune responses and tissue remodelling, also elucidating novel roles for CRP-I in the nervous system. The presence of deimination positive bands for cod CRPs varied somewhat between mucus and serum, possibly facilitati...

Research paper thumbnail of Prevention of congenital rubella in Iceland by antibody screening and immunization of seronegative females

A programme to eradicate congenital rubella from Iceland was started in 1979, based on (1) screen... more A programme to eradicate congenital rubella from Iceland was started in 1979, based on (1) screening ofallfemales aged 12-45yearsfor rubella antibodies and (2) vaccination of all seronegative persons with the RA /27/3 rubella vaccine, given free of charge. Thus, individualprotection was offered to all who needed it. The collection ofserum samples was planned to last for 2 years while, simultaneously, the already established rubella screening and immunization programmes for 12-year-old schoolgirls and pregnant women continued. During assessment in 1983, 95.2% offemales in the first 7 age groups (by now aged 14-20 years) participating in the school programme had been tested and 80.4% of them were found to be naturally immune. Of the seronegatives, 93.7% were subsequently vaccinated, thus giving an overall immunity rate of98.8%. Among the women in the peak of the childbearing period (by now aged 21-35 years), 84.4% had been tested and 92.7% werefound to be naturally immune; vaccination of 61.4% ofseronegative individuals then gave an overall immunity rate of 97.2% for this age group. Ifit is assumed that the natural immunity rate offemales still untested is like that ofthe above groups, then thepercentage ofnon-immunepersons is atpresent 2.1 % in theyounger group and 3.4% in the older.

Research paper thumbnail of Detection of Renibacterium salmoninarum in salmonid kidney samples: a comparison of results using double-sandwich ELISA and isolation on selective medium

Journal of Fish Diseases, 1993

A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L.... more A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L., brown trout, Salmo trutta L., Aretic charr. Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). were screened for Renibacterium salmoninarum using double-sandwich ELISA and bacterial isolation. For bacterial isolation, samples were homogenized, washed, plated onto S-KDM and incubated for 12 weeks. Samples for ELISA were kept frozen until tested. Alter thawing, 25% homogenates in PBS were heated at KIOT for 15 min in the presence (2 5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisole) and then centrifugcd. The supernatant was tested with polyclonal antibodies against whole bacterium in a double-sandwich ELISA. In seven out of 12 groups tested, all samples wore negative in both tests. Positive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in fouT out of these five groups. The ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.

Research paper thumbnail of The Carbohydrate Moiety of IgM From Atlantic Salmon (Salmo salar L.)

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1997

The carbohydrate moiety of salmon IgM was estimated to be about 12.5% of the total molecular weig... more The carbohydrate moiety of salmon IgM was estimated to be about 12.5% of the total molecular weight of salmon IgM based on SDS-PAGE analysis and Յ8.0% based on FACE analysis. The carbohydrate moiety was restricted to the heavy chain and was all N-linked. Six different oligosaccharides were identified using the FACE oligosaccharide profiling technique. Monosaccharide composition analysis, as well as digestion with endoglycosidase H, suggested that the oligosaccharides were mainly of the complex type rather than high mannose type. Removal of about 80% of the carbohydrate affected the sensitivity of IgM to trypsin but had no effects on antigen binding or the complement fixation ability of anti s-RBC IgM. comp biochem physiol 116B; 4:423-430, 1997.

Research paper thumbnail of Measures applied to control Renibacterium salmoninarum infection in Atlantic salmon: a retrospective study of two sea ranches in Iceland

Aquaculture, 2000

This study describes the success of broodstock culling in controlling Renibacterium salmoninarum ... more This study describes the success of broodstock culling in controlling Renibacterium salmoninarum infection on two sea ranches in Iceland. On both ranches, the overall percentage of positive broodfish was around 35% when the program was initiated. After a few years of broodstock culling, the prevalence figures for broodfish declined and remained below 2.0%. The progeny of the fish subjected to culling, sampled during smoltification, always tested negative for R. salmoninarum. As infected broodfish were detected in most years, there was a continuous risk of Ž. bacterial kidney disease BKD epidemics on both ranches.

Research paper thumbnail of Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmonid fish, detected by nested reverse transcription-PCR of 16S rRNA sequences

Applied and Environmental Microbiology, 1994

An assay based on reverse transcription and nested PCR amplification of hypervariable regions wit... more An assay based on reverse transcription and nested PCR amplification of hypervariable regions within the 16S rRNA sequence was used to specifically detect Renibacterium salmoninarum, the slowly growing causative agent of bacterial kidney disease in salmonid fish. This assay detected 1 to 10 bacteria per sample and took 1 to 2 days to perform. The assay was used to detect R. salmoninarum in ovarian fluid obtained from naturally infected fish. The assay was unreliable when it was used to examine kidney tissue.

Research paper thumbnail of A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus hippoglossus L.)

Fish & Shellfish Immunology, 2018

A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus... more A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus hippoglossus L.

Research paper thumbnail of Detection of Renibacterium salmoninarum in salmonid kidney samples: a comparison of results using double-sandwich ELISA and isolation on selective medium

Journal of Fish Diseases, May 1, 1993

A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L.... more A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L., brown trout, Salmo trutta L., Aretic charr. Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). were screened for Renibacterium salmoninarum using double-sandwich ELISA and bacterial isolation. For bacterial isolation, samples were homogenized, washed, plated onto S-KDM and incubated for 12 weeks. Samples for ELISA were kept frozen until tested. Alter thawing, 25% homogenates in PBS were heated at KIOT for 15 min in the presence (2 5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisole) and then centrifugcd. The supernatant was tested with polyclonal antibodies against whole bacterium in a double-sandwich ELISA. In seven out of 12 groups tested, all samples wore negative in both tests. Positive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in fouT out of these five groups. The ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.

Research paper thumbnail of Evaluation of cross protection by vaccines against atypical and typical furunculosis in Atlantic salmon, Salmo salar L

Journal of Fish Diseases, 1997

In Iceland, farmed salmonids are vaccinated against A. salmonicida ssp. achromogenes (Asa), which... more In Iceland, farmed salmonids are vaccinated against A. salmonicida ssp. achromogenes (Asa), which causes atypical furunculosis and is endemic in local waters. Classical furunculosis, caused by A. salmonicida ssp. salmonicida (Ass), was not diagnosed in this country until June 1995. In the present study, protection in experimental challenges against atypical and classical furunculosis in Atlantic salmon vaccinated with an autogenous Asa bacterin (Iceland Biojec.OO, IBOO), a commercial furunculosis vaccine (Biojec.1500), or a mixture of both vaccines was compared. The results showed that both vaccines gave protection against an injection challenge with Asa. However, better protection was obtained with the IBOO (homologous) vaccine. Infection of Asa by cohabitation could not be established in fresh water. Fish vaccinated with Biojec.1500 or with both vaccines simultaneously were equally well protected against Ass in a cohabitation challenge. On the other hand, no protection against cla...

Research paper thumbnail of Effects of bacterial treatment at early stages of Atlantic cod (Gadus morhuaL.) on larval survival and development

Journal of Applied Microbiology, 2010

Aims: To assess the effects of bacterial treatment at the earliest stages of cod rearing on the m... more Aims: To assess the effects of bacterial treatment at the earliest stages of cod rearing on the microbial load, larval development and performance, testing three bacterial strains (Carnobacterium divergens V41, Arthrobacter sp. and Enterococcus sp.) in vivo that were previously shown to have inhibitory potential towards fish pathogens in vitro. Methods and Results: A bacterial mixture was added eight times to the rearing water from the prehatch to the mid-larval stage (a 38-day period). Microbiological analysis of ova, larvae and rearing water was performed regularly. Larval performance and development were evaluated by survival rate, hypersalinity tolerance and physiological measurements. Different larval survival rates were observed within and between treatments, and possibly explained by variations in larval microflora and established probionts. Larvae from one silo, which had been bathed in the bacterial suspension, showed the highest survival rate (42AE1%), lowest Vibrio levels, and were significantly heavier (19AE3%) and more stress tolerant than control larvae (P < 0AE01). This coincided with the intestinal establishment of two of the tested bacteria. Conclusions: Arthrobacter and Enterococcus strains added regularly to the rearing water from the postfertilized egg stage can become established in larval gastrointestinal tract. The Enterococcus strain was associated with increased larval growth, performance and microflora control, indicating its probiotic nature. Significance and Impact of the Study: Regular application of autochthonous probionts may promote larval welfare, development and stress tolerance at early stages, hence increasing production yield in intensive cod larviculture.

Research paper thumbnail of Gadus morhua L: Acute phase responses in larvae and juveniles

Fish & Shellfish Immunology, 2013

Research paper thumbnail of Epidemiology of Renibacterium salmoninarum in Scotland and the potential for compartmentalised management of salmon and trout farming areas

Aquaculture, 2012

Bacterial kidney disease (BKD) (caused by Renibacterium salmoninarum) can result in significant m... more Bacterial kidney disease (BKD) (caused by Renibacterium salmoninarum) can result in significant mortality in Scottish salmon farms, but is considered to be a minor issue on trout farms. Controlling R. salmoninarum infection in trout to protect farmed salmon would be effective only if the risk posed from trout is significant both in absolute terms and relative to other potential sources of R. salmoninarum. To assess this, three complementary reviews are undertaken: review of data quality on BKD in Scotland and the national level prevalence and dynamics these data imply; case studies of recent BKD outbreaks in Scotland; and an assessment of the epidemiological and management factors that maintain and spread R. salmoninarum within and between the trout and salmon industries. These are then synthesised into a conclusion on the factors required for control of BKD in salmon. Most observed spread of R. salmoninarum occurred within single species or even companies, so the majority of cases in farmed salmon are linked to other salmon (and not to trout) farms. There is substantive geographical separation of areas of production for trout and salmon and transmission between salmon and trout networks is limited. The bacterium does not survive long in water so hydrodynamic transmission is likely to be localised. Currently R. salmoninarum is extremely rare in Scottish wild fish; this has not always been the case. Wild fish therefore probably play a limited role, but might act as reservoirs or vectors. The general conclusion is that to a large extent the transmission of R. salmoninarum in salmon and trout production can be separated and so there is potential to compartmentalise BKD controls, either by host species or geographical area.

Research paper thumbnail of Experimental challenges with Renibacterium salmoninarum in Arctic charr Salvelinus alpinus

Diseases of Aquatic Organisms, Mar 30, 2017

Arctic charr Salvelinus alpinus L. is an important species in Icelandic aquaculture and the most ... more Arctic charr Salvelinus alpinus L. is an important species in Icelandic aquaculture and the most common wild salmonid in Iceland. A study on the course of infection with the bacterium Renibacterium salmoninarum was conducted using 3 different challenge methods in brackish and fresh water. Bacterial isolation, ELISA and PCR tests were used for detection of the bacterium in multiple organ samples. In an experiment, run for 34 wk in brackish water, infection was established by intraperitoneal injection with 5 × 10 6 colony forming units (CFU) fish −1. There were external and internal symptoms of bacterial kidney disease (BKD) and mortalities between 6 and 13 wk after injection. A cohabitation trial was run simultaneously and infection was well established after 4 wk, as demonstrated by the detection methods applied. Symptoms of BKD were not seen and all but 1 cohabitant survived. In a separate experiment, infection was established by pumping a fixed amount of water from a tank with fingerlings infected by intraperitoneal injection into tanks with naïve fish, in fresh or brackish water, for 6 wk. Fish in the inflow tanks were reared for an additional 3 wk. There were neither macroscopic symptoms nor mortalities. ELISA and PCR tests showed that infection started to take hold after 3 wk. The challenge trials demonstrated that Arctic charr is susceptible to R. salmoninarum. Cohabitation and inflow of water from tanks with infected fish provide useful models for further studies on R. salmoninarum infection acquired in a natural way in Arctic charr.

Research paper thumbnail of Evaluation of a semi-nested PCR for detection of Renibacterium salmoninarum in samples from kidney, gill and ovarian fluid of Atlantic salmon broodfish

Icelandic Agricultural Sciences, 2013

A semi-nested PCR (snPCR) for detection of Renibacterium salmoninarum that causes bacterial kidne... more A semi-nested PCR (snPCR) for detection of Renibacterium salmoninarum that causes bacterial kidney disease (BKD) in salmonids was constructed. The efficacy of the snPCR was evaluated by comparison with nested PCR (nPCR) and two ELISA methods on kidney, ovarian fluid and gill samples collected from Atlantic salmon broodfish with escalating disease. The PCR methods using a conventional isolation kit identified equal numbers of positive samples, or 30%, with acceptable agreement. The ratio of positive kidney samples in PCR increased significantly, 42.5% in snPCR and 45% in nPCR, when an FTA minicard was used for DNA isolation. ELISA, using polyclonal antibodies, detected the highest number of positive samples (65%) and ELISA using monoclonal antibodies the lowest (17.5%). Ovarian fluid and gills gave inadequate results and cannot replace kidney samples for determination of R. salmoninarum infection in Atlantic salmon broodfish.

Research paper thumbnail of Extracellular vesicles, deiminated protein cargo and microRNAs are novel serum biomarkers for environmental rearing temperature in Atlantic cod (Gadus morhua L.)

Aquaculture Reports, 2020

The Open University's repository of research publications and other research outputs Extracellula... more The Open University's repository of research publications and other research outputs Extracellular vesicles, deiminated protein cargo and microRNAs are novel serum biomarkers for environmental rearing temperature in Atlantic cod (Gadus morhua L.)

Research paper thumbnail of Extracellular vesicles from cod (Gadus morhua L.) mucus contain innate immune factors and deiminated protein cargo

Developmental & Comparative Immunology, 2019

Extracellular vesicles are released from cells and participate in cell communication via transfer... more Extracellular vesicles are released from cells and participate in cell communication via transfer of protein and genetic cargo derived from the parent cells. EVs play roles in normal physiology and immunity and are also linked to various pathological processes. Peptidylarginine deiminases (PADs) are phylogenetically conserved enzymes with physiological and pathophysiological roles. PADs cause post-translational protein deimination, resulting in structural and, in some cases, functional changes in target proteins and are also linked to EV biogenesis. This study describes for the first time EVs isolated from cod mucosa. Mucosal EVs were characterised by electron microscopy, nanoparticle tracking analysis and EV-specific surface markers. Cod mucosal EVs were found to carry PAD, complement component C3 and C-reactive proteins. C3 was found to be deiminated in both whole mucus and mucosal EVs, with some differences, and further 6 deiminated immune and cytoskeletal proteins were identified in EVs by LC-MS/MS analysis. As mucosal surfaces of teleost fish reflect human mucosal surfaces, these findings may provide useful insights into roles of EVs in mucosal immunity throughout phylogeny. Highlights  Extracellular vesicles (EVs) are described for the first time in cod mucosa  EVs from cod mucosa contain complement component C3, CRP-I and CRP-II  Deiminated forms of complement component C3 are exported in cod mucosal EVs  Deiminated protein cargo of cod mucosal EVs includes cytoskeletal and immune proteins

Research paper thumbnail of Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny - Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.)

Developmental & Comparative Immunology, 2018

Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny... more Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny-Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.

Research paper thumbnail of Post-translational Protein Deimination in Cod (Gadus morhua L.) Ontogeny Novel Roles in Tissue Remodelling and Mucosal Immune Defences?

Developmental and comparative immunology, Jan 13, 2018

Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophys... more Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophysiological roles conserved throughout phylogeny. PADs promote post-translational deimination of protein arginine to citrulline, altering the structure and function of target proteins. Deiminated proteins were detected in the early developmental stages of cod from 11 days post fertilisation to 70 days post hatching. Deiminated proteins were present in mucosal surfaces and in liver, pancreas, spleen, gut, muscle, brain and eye during early cod larval development. Deiminated protein targets identified in skin mucosa included nuclear histones; cytoskeletal proteins such as tubulin and beta-actin; metabolic and immune related proteins such as galectin, mannan-binding lectin, toll-like receptor, kininogen, Beta2-microglobulin, aldehyde dehydrogenase, bloodthirsty and preproapolipoprotein A-I. Deiminated histone H3, a marker for anti-pathogenic neutrophil extracellular traps, was particularly el...

Research paper thumbnail of Rannsóknir eru undirstaða þróunar og hagsældar í landbúnaði

Rannsóknir og þróun eru undirstaða allra atvinnugreina. Atvinnugrein sem heldur ekki í við framfa... more Rannsóknir og þróun eru undirstaða allra atvinnugreina. Atvinnugrein sem heldur ekki í við framfarir og þróun þrífst ekki eða dafnar til lengdar. Á Tilraunastöð Háskóla Íslands í meinafraeði að Keldum eru stundaðar rannsóknir sem tengjast dýraheilbrigði og sjúkdómum í dýrum og mönnum. Þar er veitt ráðgjöf og þjónusta í þágu heilbrigðiseftirlits, sjúkdómagreininga og sjúkdóma­ varna fyrir búfé, eldisfiska og önnur dýr. Nemar í líffraeði, lífefnafraeði, lífeindafraeði og dýralaekningum vinna rannsóknarverkefni á fraeða­ sviðum stofnunarinnar sem hluta af grunn­ eða framhaldsnámi sínu. Með vaxandi innflutningi, hnatt­ vaeðingu og hlýnandi loftslagi má gera ráð fyrir að nýir smitsjúkdómar berist til landsins í auknum maeli. Fyrir utan haettulega smitsjúkdóma sem herja á búpening og geta valdið fjárhagslegu tjóni eru margir af varasömustu smit­ sjúkdómum í mönnum svokallaðar súnur (zoonosis), en það eru sýklar sem smitast úr dýrum í fólk (s.s. fuglaflensa, svínaflensa, ebólaveira og flei...

Research paper thumbnail of Survival and humoral antibody response of Atlantic salmon, Salmo salar L., vaccinated against Aeromonas salmonicida ssp. achromogenes

Journal of Fish Diseases, 1997

(Holt, Krieg, Sneath, Staley & Williams 1994): ssp. Atlantic salmon were vaccinated against A... more (Holt, Krieg, Sneath, Staley & Williams 1994): ssp. Atlantic salmon were vaccinated against Aeromonas salmonicida, ssp. achromogenes, ssp. masoucida and salmonicida ssp. achromogenes (Asa) by injection with ssp. smithia. The causative agent of furunculosis in three vaccines developed in our laboratory and an salmonid fish is A. salmonicida ssp. salmonicida, with autogenous bacterin (IcelandBiojec.OO, IBOO) the strains being referred to as typical. Strains of the produced by a commercial vaccine producer. The other subspecies are termed atypical. humoral antibody responses to bacterial antigens were In Iceland, atypical furunculosis caused by monitored by ELISA and Western blotting. The fish A. salmonicida ssp. achromogenes is an endemic disease were challenged by infection with Asa 6 and 12 weeks causing high mortality on fish farms using brackish post-vaccination. Protection was induced in all water for rearing salmonid fish and in captive cod of groups of vaccinated fish. The protection achieved wild origin cultivated in sea cages. Furthermore, the was time-dependent. The autogenous bacterin, susceptibility of halibut to the bacterium has been IBOO, induced a protective immune response later shown by experimental infection. The bacterium has than our experimental vaccines. All the vaccines tested been isolated from wild marine fish species and induced specific antibody response that increased clinical signs are frequently detected in infected wild between 6 and 12 weeks after vaccination. The salmonids. The disease is systemic and external signs antibody response was mainly directed against the A- are similar to furunculosis including haemorrhages layer protein, but antibodies to other bacterial and lesions (furuncles) in skin and muscle

Research paper thumbnail of Pentraxins CRP-I and CRP-II are post-translationally deiminated and differ in tissue specificity in cod (Gadus morhua L.) ontogeny

Developmental and comparative immunology, Jan 16, 2018

Pentraxins are fluid phase pattern recognition molecules that form an important part of the innat... more Pentraxins are fluid phase pattern recognition molecules that form an important part of the innate immune defence and are conserved between fish and human. In Atlantic cod (Gadus morhua L.), two pentraxin-like proteins have been described, CRP-I and CRP-II. Here we show for the first time that these two CRP forms are post-translationally deiminated (an irreversible conversion of arginine to citrulline) and differ with respect to tissue specific localisation in cod ontogeny from 3 to 84 days post hatching. While both forms are expressed in liver, albeit at temporally differing levels, CRP-I shows a strong association with nervous tissue while CRP-II is strongly associated to mucosal tissues of gut and skin. This indicates differing roles for the two pentraxin types in immune responses and tissue remodelling, also elucidating novel roles for CRP-I in the nervous system. The presence of deimination positive bands for cod CRPs varied somewhat between mucus and serum, possibly facilitati...

Research paper thumbnail of Prevention of congenital rubella in Iceland by antibody screening and immunization of seronegative females

A programme to eradicate congenital rubella from Iceland was started in 1979, based on (1) screen... more A programme to eradicate congenital rubella from Iceland was started in 1979, based on (1) screening ofallfemales aged 12-45yearsfor rubella antibodies and (2) vaccination of all seronegative persons with the RA /27/3 rubella vaccine, given free of charge. Thus, individualprotection was offered to all who needed it. The collection ofserum samples was planned to last for 2 years while, simultaneously, the already established rubella screening and immunization programmes for 12-year-old schoolgirls and pregnant women continued. During assessment in 1983, 95.2% offemales in the first 7 age groups (by now aged 14-20 years) participating in the school programme had been tested and 80.4% of them were found to be naturally immune. Of the seronegatives, 93.7% were subsequently vaccinated, thus giving an overall immunity rate of98.8%. Among the women in the peak of the childbearing period (by now aged 21-35 years), 84.4% had been tested and 92.7% werefound to be naturally immune; vaccination of 61.4% ofseronegative individuals then gave an overall immunity rate of 97.2% for this age group. Ifit is assumed that the natural immunity rate offemales still untested is like that ofthe above groups, then thepercentage ofnon-immunepersons is atpresent 2.1 % in theyounger group and 3.4% in the older.

Research paper thumbnail of Detection of Renibacterium salmoninarum in salmonid kidney samples: a comparison of results using double-sandwich ELISA and isolation on selective medium

Journal of Fish Diseases, 1993

A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L.... more A total of 1239 kidney samples from four species of salmonid rtsh, AUantie salmon, Salmo salar L., brown trout, Salmo trutta L., Aretic charr. Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). were screened for Renibacterium salmoninarum using double-sandwich ELISA and bacterial isolation. For bacterial isolation, samples were homogenized, washed, plated onto S-KDM and incubated for 12 weeks. Samples for ELISA were kept frozen until tested. Alter thawing, 25% homogenates in PBS were heated at KIOT for 15 min in the presence (2 5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisole) and then centrifugcd. The supernatant was tested with polyclonal antibodies against whole bacterium in a double-sandwich ELISA. In seven out of 12 groups tested, all samples wore negative in both tests. Positive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in fouT out of these five groups. The ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.

Research paper thumbnail of The Carbohydrate Moiety of IgM From Atlantic Salmon (Salmo salar L.)

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1997

The carbohydrate moiety of salmon IgM was estimated to be about 12.5% of the total molecular weig... more The carbohydrate moiety of salmon IgM was estimated to be about 12.5% of the total molecular weight of salmon IgM based on SDS-PAGE analysis and Յ8.0% based on FACE analysis. The carbohydrate moiety was restricted to the heavy chain and was all N-linked. Six different oligosaccharides were identified using the FACE oligosaccharide profiling technique. Monosaccharide composition analysis, as well as digestion with endoglycosidase H, suggested that the oligosaccharides were mainly of the complex type rather than high mannose type. Removal of about 80% of the carbohydrate affected the sensitivity of IgM to trypsin but had no effects on antigen binding or the complement fixation ability of anti s-RBC IgM. comp biochem physiol 116B; 4:423-430, 1997.

Research paper thumbnail of Measures applied to control Renibacterium salmoninarum infection in Atlantic salmon: a retrospective study of two sea ranches in Iceland

Aquaculture, 2000

This study describes the success of broodstock culling in controlling Renibacterium salmoninarum ... more This study describes the success of broodstock culling in controlling Renibacterium salmoninarum infection on two sea ranches in Iceland. On both ranches, the overall percentage of positive broodfish was around 35% when the program was initiated. After a few years of broodstock culling, the prevalence figures for broodfish declined and remained below 2.0%. The progeny of the fish subjected to culling, sampled during smoltification, always tested negative for R. salmoninarum. As infected broodfish were detected in most years, there was a continuous risk of Ž. bacterial kidney disease BKD epidemics on both ranches.

Research paper thumbnail of Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmonid fish, detected by nested reverse transcription-PCR of 16S rRNA sequences

Applied and Environmental Microbiology, 1994

An assay based on reverse transcription and nested PCR amplification of hypervariable regions wit... more An assay based on reverse transcription and nested PCR amplification of hypervariable regions within the 16S rRNA sequence was used to specifically detect Renibacterium salmoninarum, the slowly growing causative agent of bacterial kidney disease in salmonid fish. This assay detected 1 to 10 bacteria per sample and took 1 to 2 days to perform. The assay was used to detect R. salmoninarum in ovarian fluid obtained from naturally infected fish. The assay was unreliable when it was used to examine kidney tissue.

Research paper thumbnail of A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus hippoglossus L.)

Fish & Shellfish Immunology, 2018

A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus... more A novel ladder-like lectin relates to sites of mucosal immunity in Atlantic halibut (Hippoglossus hippoglossus L.