Infectious Pancreatic Necrosis (IPN)

What is Infectious Pancreatic Necrosis?

Infectious Pancreatic Necrosis (IPN) is a severe and highly contagious viral disease of salmonids that usually affects the fish during its early life stages and in the first phase in the sea. The condition is caused by the infectious pancreatic necrosis virus (IPNV) and can lead to high levels of mortality.

The virus is mainly spread through horizontal transmission (i.e., via infected water and from one individual to the next), although a vertical path of spread has also been suggested (i.e., from parents to the offspring). The outbreaks are usually sudden and can often cause a high number of mortalities and significant economic losses. Following infection, any animals that survive the outbreak can develop a lifelong illness.

Figure 1: Manhattan plot. Showing the genome-wide association of IPNV resistance in our populations. The figure shows the association of thousands of genetic markers tested against this pathogen. Each chromosome is designated with a different color. The information from a significant QTL (chromosome 26), has been implemented in our breeding program. This has resulted in breeding for fish with high resistance against this disease.

QTL Selections

Benchmark Genetics offers IPN robust fish using QTL selection, which started in 2007 (Figure 1). Resistance to IPN is highly heritable and can, to a large degree, be explained by genetic variations identified in a single gene. Across salmon populations tested in Benchmark Genetics, around 80–90% of the animals that carry the resistant form of the gene survives the challenge tests (Figure 2).

Benchmark Genetics has QTL IPN as a standard trait in all its products, and we have ensured that all ova carry the resistant QTL combination. Before and in parallel with QTL implementation, the company has been selecting for IPN resistant based on the family level since 2004. The introduction of the IPN QTL has resulted in a significant reduction in numbers of IPN cases.

Figure 2: This figure shows the relation between the presence (Q) or absence (q) of IPN QTL. It also shows the mortality level in our tested fish. By using parents that carry the QTL genotype in our ova production, we can expect high survival of its offspring

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