Cardiomyopathy Syndrome (CMS)

What is Cardiomyopathy Syndrome?

Cardiomyopathy Syndrome (CMS) is a severe heart disease of Atlantic salmon caused by the Piscine myocarditis virus (PMCV). The fish is usually affected during late production stages, mainly in the second year after transferring to sea. The economic losses caused by a CMS outbreak can be significant. Over the past few years, the frequency of CMS outbreaks has increased throughout Norway, Scotland and the Faroe Islands. As of now, there are no effective vaccines or treatments.

manPlot-1
Figure 1: Manhattan plots. Showing the genome-wide association of CMS resistance in our populations. The figure shows the association of thousands of genetic markers tested against the CMS resistance. Each chromosome is designated with a different color. The information from significant QTL (on chromosomes 12 and 27), have been implemented in our breeding program. This has resulted in breeding for fish with high resistance against this disease.

The CMS trait

Benchmark Genetics offers CMS robust fish using QTL and GS, which was initiated in 2018 and 2020 (Hillestad and Moghadam, 2019). A significant QTL, that affects the severity of the infection and the damage to the heart has been detected in our populations (Figure 1) (Hillestad et al., 2020).

In challenge tests, a high frequency of the fish carrying the favorable version of the QTL showed low to undetectable levels of the virus, with little signs of heart damage. In contrast, fish with the unfavorable copy of the QTL had substantially higher loads of the virus and severe cardiac damages.

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