Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Feb 21;48(1):12.
doi: 10.1186/s13567-017-0416-7.

Experimental infections of different carp strains with the carp edema virus (CEV) give insights into the infection biology of the virus and indicate possible solutions to problems caused by koi sleepy disease (KSD) in carp aquaculture

Mikolaj Adamek  1 , Anna Oschilewski  2 , Peter Wohlsein  3 , Verena Jung-Schroers  2 , Felix Teitge  2 , Andy Dawson  2   4 , David Gela  5 , Veronika Piackova  5 , Martin Kocour  5 , Jerzy Adamek  6 , Sven M Bergmann  7 , Dieter Steinhagen  2
Affiliations

Experimental infections of different carp strains with the carp edema virus (CEV) give insights into the infection biology of the virus and indicate possible solutions to problems caused by koi sleepy disease (KSD) in carp aquaculture

Mikolaj Adamek et al. Vet Res. .

Abstract

Outbreaks of koi sleepy disease (KSD) caused by carp edema virus (CEV) may seriously affect populations of farmed common carp, one of the most important fish species for global food production. The present study shows further evidence for the involvement of CEV in outbreaks of KSD among carp and koi populations: in a series of infection experiments, CEV from two different genogroups could be transmitted to several strains of naïve common carp via cohabitation with fish infected with CEV. In recipient fish, clinical signs of KSD were induced. The virus load and viral gene expression results confirm gills as the target organ for CEV replication. Gill explants also allowed for a limited virus replication in vitro. The in vivo infection experiments revealed differences in the virulence of the two CEV genogroups which were associated with infections in koi or in common carp, with higher virulence towards the same fish variety as the donor fish. When the susceptibility of different carp strains to a CEV infection and the development of KSD were experimentally investigated, Amur wild carp showed to be relatively more resistant to the infection and did not develop clinical signs for KSD. However, the resistance could not be related to a higher magnitude of type I IFN responses of affected tissues. Despite not having a mechanistic explanation for the resistance of Amur wild carp to KSD, we recommend using this carp strain in breeding programs to limit potential losses caused by CEV in aquaculture.

PubMed Disclaimer

Figures

Figure 1
Figure 1
CEV load and replication in tissues of common carp affected by KSD. Carp edema virus load (A) was measured by qPCR as copy numbers of virus specific DNA. As a surrogate for CEV replication, the expression of the gene encoding the CEV core protein P4a (CEV P4a) was determined (B). The data on virus load and expression of viral mRNA are shown as box plots indicating the range of 25–75% in the box (±minimum and maximum values) of genome copies in 250 ng of isolated DNA from n = 4 fish (virus load), or as the copy number of mRNA encoding the viral P4a gene normalised against 100 000 copies of the carp 40S ribosomal protein S11. Symbols “+” and “□” indicate mean and median, respectively. Different letters indicate significant differences at p ≤ 0.05 between the carp tissues.
Figure 2
Figure 2
Gills of KSD affected common carp (donor fish). Clubbing and fusion of secondary gill lamellae with complete occlusion of the interlamellar spaces due to accumulation of cellular debris (white arrows), and hypertrophy of epithelial cells (white arrowheads); Note cytoplasmatic eosinophilic inclusions (black arrowheads); black arrows = lamellar capillaries; HE, bar = 40 µm.
Figure 3
Figure 3
Susceptibility of different strains of carp to an infection with CEV from the carp genogroup I (Experiment no. Co II). Depicted is carp edema virus load (A) and replication (B) in the gills of koi (Koi) and common carp from the strains Amur wild carp (AS), Ropsha (Rop) and Prerov (PS) during cohabitation with carp affected by KSD. CEV load was measured by qPCR as copy numbers of virus specific DNA. As a surrogate for CEV replication, the expression of mRNA encoding the gene of the CEV core protein P4a (CEV P4a) was determined. The data on virus load and expression of viral mRNA are shown as box plots indicating the range of 25–75% of the values in the box (±minimum and maximum values) of genome copies in 250 ng of isolated DNA from n = 4 fish (virus load) or of the copy number of mRNA encoding the viral P4a gene normalised against 100 000 copies of the carp 40S ribosomal protein S11 (CEV replication). Symbols “+” and “□” indicate mean and median respectively. Different letters indicate significant differences at p ≤ 0.05 between carp strains.
Figure 4
Figure 4
Susceptibility of different strains of carp to an infection with CEV from the koi, genogroup IIa (Experiment no. Co IV). Depicted is carp edema virus load (A) and replication (B) in the gills of koi (Koi) and common carp from the strains Amur wild carp (AS), Ropsha (Rop) and Prerov (PS) during cohabitation with koi affected by KSD. CEV load was measured by qPCR as copy numbers of virus specific DNA. As a surrogate for CEV replication, the expression of mRNA encoding the gene of the CEV core protein P4a (CEV P4a) was determined. The data on virus load and expression of viral mRNA are shown as box plots indicating the range of 25–75% of the values in the box (±minimum and maximum values) of genome copies in 250 ng of isolated DNA from n = 4 fish (virus load) or of the copy number of mRNA encoding the viral P4a gene normalised against 100 000 copies of the carp 40S ribosomal protein S11 (CEV replication). Symbols “+” and “□” indicate mean and median respectively. Different letters indicate significant differences at p ≤ 0.05 between carp strains.
Figure 5
Figure 5
Replication of CEV in gill explant cultures and in primary fin cultures of various carp strains. Cultures were obtained from koi (Koi) and common carp from following strains: Amur wild carp (AS), Ropsha (Rop) Prerov (PS). Cultures were infected with CEV from the carp strain for 48 h at 15 or 25 °C. The CEV was re-isolated from KSD affected carp. As a surrogate for virus replication, the expression of mRNA encoding the viral core protein P4a (CEV P4a mRNA levels) is shown as mean (+SD) copy number of the P4a gene normalised against 100 000 copies of the carp 40S ribosomal protein S11 from n = 3 cultures.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Food and Agriculture Organization of the United Nations yearbook. Fishery and Aquaculture Statistics 2012. http://www.fao.org/3/478cfa2b-90f0-4902-a836-94a5dddd6730/i3740t.pdf. Accessed 21 Jan 2017
    1. Food and Agriculture Organization of the United Nations, Fisheries and Aquaculture Department http://www.fao.org/fishery/culturedspecies/Cyprinus_carpio/en. Accessed 21 Jan 2017
    1. Bekefi E, Varadi L. Multifunctional pond fish farms in Hungary. Aquacult Int. 2007;15:227–233. doi: 10.1007/s10499-007-9090-5. - DOI
    1. Baruš V, Peňáz M, Kohlmann K. Cyprinus carpio (Linnaeus, 1758) In: Bănărescu P, Paepke HJ, editors. The Freshwater Fishes of Europe. Wiebelsheim: AULA-Verlag GmbH; 2002.
    1. Sunarto A, Rukyani A, Itami T. Indonesian experience on the outbreak of koi herpesvirus in koi and carp (Cyprinus carpio) Bull Fish Res Agen Suppl. 2005;2:15–21.

Publication types