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Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar).

Bjørgen H, Wessel Ø, Fjelldal PG, Hansen T, Sveier H, Sæbø HR, Enger KB, Monsen E, Kvellestad A, Rimstad E, Koppang EO - Vet. Res. (2015)

Bottom Line: Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals.Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation.We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.

View Article: PubMed Central - PubMed

Affiliation: Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway. havard.bjorgen@nmbu.no.

ABSTRACT
Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.

No MeSH data available.


Related in: MedlinePlus

Gross image of paraffin-embedded red focal change. Transient form with both red (asterisk) and melanised (arrowheads) changes. Scale bar = 1 cm.
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Fig2: Gross image of paraffin-embedded red focal change. Transient form with both red (asterisk) and melanised (arrowheads) changes. Scale bar = 1 cm.

Mentions: In general, each affected fillet had only one focal change, but occasionally there were multiple foci with varying degrees of discolouration within a single focal change. Foci extended from 1–3 cm and could involve 2–6 myotomes. Incisions through foci revealed extension of the discolouration deep into the muscle (Figures 1B and D). The changes generally appeared as either red or melanised (Figure 1 and Table 3). Two changes classified as red contained both red and melanised discolouration (Figure 2).Figure 2


Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar).

Bjørgen H, Wessel Ø, Fjelldal PG, Hansen T, Sveier H, Sæbø HR, Enger KB, Monsen E, Kvellestad A, Rimstad E, Koppang EO - Vet. Res. (2015)

Gross image of paraffin-embedded red focal change. Transient form with both red (asterisk) and melanised (arrowheads) changes. Scale bar = 1 cm.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4562189&req=5

Fig2: Gross image of paraffin-embedded red focal change. Transient form with both red (asterisk) and melanised (arrowheads) changes. Scale bar = 1 cm.
Mentions: In general, each affected fillet had only one focal change, but occasionally there were multiple foci with varying degrees of discolouration within a single focal change. Foci extended from 1–3 cm and could involve 2–6 myotomes. Incisions through foci revealed extension of the discolouration deep into the muscle (Figures 1B and D). The changes generally appeared as either red or melanised (Figure 1 and Table 3). Two changes classified as red contained both red and melanised discolouration (Figure 2).Figure 2

Bottom Line: Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals.Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation.We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.

View Article: PubMed Central - PubMed

Affiliation: Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway. havard.bjorgen@nmbu.no.

ABSTRACT
Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.

No MeSH data available.


Related in: MedlinePlus