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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 pathological changes of white muscle. (A) A red focal change in the muscle of the craniodorsal region of the abdominal wall. (B) An incision through a red focal change showing discolouration extending deep into the fillet. (C) A melanised focal change detected in the same anatomical location in a different fish. (D) A melanised focal change with extensive amounts of a whitish tissue extending into the depth of the fillet. (E) A muscle fillet with two faint melanised lesions (arrows) and one red focal change (arrowheads).
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Fig1: Gross pathological changes of white muscle. (A) A red focal change in the muscle of the craniodorsal region of the abdominal wall. (B) An incision through a red focal change showing discolouration extending deep into the fillet. (C) A melanised focal change detected in the same anatomical location in a different fish. (D) A melanised focal change with extensive amounts of a whitish tissue extending into the depth of the fillet. (E) A muscle fillet with two faint melanised lesions (arrows) and one red focal change (arrowheads).

Mentions: All fish of all groups were in normal condition and with no apparent external pathological changes. Following autopsy, large discoloured focal changes in the white muscle, mainly in the cranio-dorsal and abdominal regions, were found in Groups A, B, C, D and E, but not in Groups F, G and H, including fish kept in in-house tanks and in wild-caught individuals (Figure 1 and Table 3). One faintly pigmented focus, approximately 2 mm in diameter, was detected in one individual in Group F. This change would have gone unnoticed under normal abattoir conditions.Figure 1


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 pathological changes of white muscle. (A) A red focal change in the muscle of the craniodorsal region of the abdominal wall. (B) An incision through a red focal change showing discolouration extending deep into the fillet. (C) A melanised focal change detected in the same anatomical location in a different fish. (D) A melanised focal change with extensive amounts of a whitish tissue extending into the depth of the fillet. (E) A muscle fillet with two faint melanised lesions (arrows) and one red focal change (arrowheads).
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig1: Gross pathological changes of white muscle. (A) A red focal change in the muscle of the craniodorsal region of the abdominal wall. (B) An incision through a red focal change showing discolouration extending deep into the fillet. (C) A melanised focal change detected in the same anatomical location in a different fish. (D) A melanised focal change with extensive amounts of a whitish tissue extending into the depth of the fillet. (E) A muscle fillet with two faint melanised lesions (arrows) and one red focal change (arrowheads).
Mentions: All fish of all groups were in normal condition and with no apparent external pathological changes. Following autopsy, large discoloured focal changes in the white muscle, mainly in the cranio-dorsal and abdominal regions, were found in Groups A, B, C, D and E, but not in Groups F, G and H, including fish kept in in-house tanks and in wild-caught individuals (Figure 1 and Table 3). One faintly pigmented focus, approximately 2 mm in diameter, was detected in one individual in Group F. This change would have gone unnoticed under normal abattoir conditions.Figure 1

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