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Comparison of the resistance of selected families of common carp, Cyprinus carpio L., to koi herpesvirus: preliminary study.

Koi herpesvirus disease (KHD), caused by koi herpesvirus (KHV), is a highly infectious disease of carp, Cyprinus carpio L., usually causing high mortality (reviewed by Dixon 2008). The disease has a worldwide distribution and affects ornamental carp (koi carp) as well as common carp in both aquaculture and open waters (rivers, lakes, etc.). The disease is economically very important, having an impact on the trade in high value ornamental fish, sport fisheries and food production. Attempts have been made to reduce the economic impact of the disease by vaccination (Ronen, Perelberg, Abramowitz, Hutoran, Tinman, Bejerano, Steinitz & Kotler 2003; Perelberg, Ronen, Hutoran, Smith & Kotler 2005), but as yet no vaccine has been approved for use outside Israel. An alternative method of controlling the disease by use of resistant strains has been investigated (Shapira, Magen, Zak, Kotler, Hulata & Levavi-Sivan 2005; Zak, Perelberg, Magen, Milstein & Joseph 2007). The latter authors bred three hybrid and three pure crosses from two Hungarian and one Israeli strain of fish and reported survival rates after challenge with KHV of between 4% and 20%. Shapira et al. (2005) crossed two strains of domesticated carp with one strain of wild carp and exposed the progeny to KHV both in the laboratory and in the field. The mortalities ranged from 8.9% to 89.7% in the field trial and from 8.6% to 68.5% in the laboratory trial, and with one exception there was good comparability of survival rates of the different crosses in the two trials. To further explore the potential of producing strains of carp resistant to KHV, we have investigated the survival of a large number of carp families following exposure to the virus, and present the results here. This study is part of a larger study, which includes investigating production characteristics, the resistance of the families to Aeromonas hydrophila, post-infection changes at the genomic level (Williams, Li, Hughes, Gonzalez, Vernon, Vidal, Jeney, Jeney, Dixon, McAndrew, Bartfai, Orban, Trudeau, Rogers, Matthews, Fraser, Gracey & Cossins 2008) and proteomic level, heritability characteristics, the genetic correlation between different traits and gene linkage mapping. The production and other characteristics of the fish families will be described in full in a separate communication (Z. Jeney, unpublished data). Briefly, 96 families were produced by diallele crossing of four strains of carp (Duna, Amur, Tata and HAKI 15) maintained in a live gene bank at HAKI, Hungary. Five females and 10 males from each strain were used to produce six families per strain cross. The families were maintained in separate tanks until they were large enough to be injected with a passive integrated transponder (PIT) tag. Twenty fish from each of 94 families (there Journal of Fish Diseases 2009, 32, 1035–1039 doi:10.1111/j.1365-2761.2009.01081.x