Efficacy and safety of an inactivated vaccine against Salmonid alphavirus (family Togaviridae)

Karlsen, Marius; Tingbø, Terje; Solbakk, Inge-Tom; Evensen, Øystein; Furevik, Anette; Aas-Eng, Anne

doi:10.1016/j.vaccine.2012.05.069

Cited by 39 publications

(24 citation statements)

References 26 publications

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“…The converse was described by Karlsen et al . () in PD vaccine trials using 1.15 × 10 8 TCID 50 /fish of SAV isolate ALV413. They obtained 87.5% cumulative mortality in intraperitoneal injected fish but negligible mortality in cohabitant fish, totally the opposite to our results.…”

Section: Discussionmentioning

confidence: 99%

Mortality and weight loss of Atlantic salmon, Salmon salar L., experimentally infected with salmonid alphavirus subtype 2 and subtype 3 isolates from Norway

Taksdal

Jensen

Böckerman

et al. 2014

Journal of Fish Diseases

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Pancreas disease (PD) caused by salmonid alphavirus (SAV) has a significant negative economic impact in the salmonid fish farming industry in northern Europe. Until recently, only SAV subtype 3 was present in Norwegian fish farms. However, in 2011, a marine SAV 2 subtype was detected in a fish farm outside the PD-endemic zone. This subtype has spread rapidly among fish farms in mid-Norway. The PD mortality in several farms has been lower than expected, although high mortality has also been reported. In this situation, the industry and the authorities needed scientific-based information about the virulence of the marine SAV 2 strain in Norway to decide how to handle this new situation. Atlantic salmon post-smolts were experimentally infected with SAV 2 and SAV 3 strains from six different PD cases in Norway. SAV 3-infected fish showed higher mortality than SAV 2-infected fish. Among the SAV 3 isolates, two isolates gave higher mortality than the third one. At the end of the experiment, fish in all SAV-infected groups had significantly lower weight than the uninfected control fish. This is the first published paper on PD to document that waterborne infection produced significantly higher mortality than intraperitoneal injection.

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Section: Discussionmentioning

confidence: 99%

Mortality and weight loss of Atlantic salmon, Salmon salar L., experimentally infected with salmonid alphavirus subtype 2 and subtype 3 isolates from Norway

Taksdal

Jensen

Böckerman

et al. 2014

Journal of Fish Diseases

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“…The IM route of infection for SAV-3 is not natural since it is expected that fish get infected either through vectors or the water itself. Challenge studies using the cohabitation model have previously been described although they have not performed according to expectations firstly because of the difficulty to induce mortalities experimentally for SAV in general [32,34,52] and secondly because the strength of virus challenge seems to be somewhat attenuated compared to IM challenge [53]. In the present study, the presence of virus at low titers in cohabitants (Figure 2b, 2 and 4 wpi) probably allowed the fish to mount a protective immune response resulting in the delay/down regulation of pathology.…”

Section: Discussionmentioning

confidence: 99%

Gene expression studies of host response to Salmonid alphavirus subtype 3 experimental infections in Atlantic salmon

Guo

Mutoloki

et al. 2012

Vet Res

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Salmonid alphavirus subtype-3 (SAV-3) infection in Atlantic salmon is exclusively found in Norway. The salmonid alphaviruses have been well characterized at the genome level but there is limited information about the host-pathogen interaction phenomena. This study was undertaken to characterize the replication and spread of SAV-3 in internal organs of experimentally infected Atlantic salmon and the subsequent innate and adaptive immune responses. In addition, suitability of a cohabitation challenge model for this virus was also examined. Groups of fish were infected by intramuscular injection (IM), cohabited (CO) or kept uninfected in a separate tank. Samples of pancreas, kidney, spleen, heart and skeletal muscles were collected at 2, 4 and 8 weeks post infection (wpi). Pathological changes were assessed by histology concurrently with viral loads and mRNA expression of immune genes by real time RT-PCR. Pathological changes were only observed in the pancreas and heart (target organs) of both IM and CO groups, with changes appearing first in the pancreas (2 wpi) in the former. Lesions with increasing severity over time coincided with high viral loads despite significant induction of IFN-α, Mx and ISG15. IFN-γ and MHC-I were expressed in all tissues examined and their induction appeared in parallel with that of IL-10. Inflammatory genes TNF-α, IL-12 and IL-8 were only induced in the heart during pathology while T cell-related genes CD3ε, CD4, CD8, TCR-α and MHC-II were expressed in target organs at 8 wpi. These findings suggest that the onset of innate responses came too late to limit virus replication. Furthermore, SAV-3 infections in Atlantic salmon induce Th1/cytotoxic responses in common with other alphaviruses infecting higher vertebrates. Our findings demonstrate that SAV-3 can be transmitted via the water making it suitable for a cohabitation challenge model.

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“…In the endemic area, with movement restriction, the PD-affected sites have been allowed to keep their fish until slaughtering time. Vaccination has been practiced in the majority of the sites in this PD endemic area; however, the efficacy and effectiveness of the currently used vaccine is debatable [29]. Conversely, vaccination is not a common practice in the PD non-endemic area (the northern part of Norway), but a stamping out policy is regulated and followed by a fallowing period [12].…”

Section: Discussionmentioning

confidence: 99%

Risk map and spatial determinants of pancreas disease in the marine phase of Norwegian Atlantic salmon farming sites

et al. 2012

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BackgroundOutbreaks of pancreas disease (PD) greatly contribute to economic losses due to high mortality, control measures, interrupted production cycles, reduced feed conversion and flesh quality in the aquaculture industries in European salmon-producing countries. The overall objective of this study was to evaluate an effect of potential factors contributing to PD occurrence accounting for spatial congruity of neighboring infected sites, and then create quantitative risk maps for predicting PD occurrence. The study population included active Atlantic salmon farming sites located in the coastal area of 6 southern counties of Norway (where most of PD outbreaks have been reported so far) from 1 January 2009 to 31 December 2010.ResultsUsing a Bayesian modeling approach, with and without spatial component, the final model included site latitude, site density, PD history, and local biomass density. Clearly, the PD infected sites were spatially clustered; however, the cluster was well explained by the covariates of the final model. Based on the final model, we produced a map presenting the predicted probability of the PD occurrence in the southern part of Norway. Subsequently, the predictive capacity of the final model was validated by comparing the predicted probabilities with the observed PD outbreaks in 2011.ConclusionsThe framework of the study could be applied for spatial studies of other infectious aquatic animal diseases.

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Efficacy and safety of an inactivated vaccine against Salmonid alphavirus (family Togaviridae)

Cited by 39 publications

References 26 publications

Mortality and weight loss of Atlantic salmon, Salmon salar L., experimentally infected with salmonid alphavirus subtype 2 and subtype 3 isolates from Norway

Mortality and weight loss of Atlantic salmon, Salmon salar L., experimentally infected with salmonid alphavirus subtype 2 and subtype 3 isolates from Norway

Gene expression studies of host response to Salmonid alphavirus subtype 3 experimental infections in Atlantic salmon

Risk map and spatial determinants of pancreas disease in the marine phase of Norwegian Atlantic salmon farming sites

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