Studying the Genetics of Resistance to CyHV-3 Disease Using Introgression from Feral to Cultured Common Carp Strains

Abstract

Sustainability and further development of aquaculture production are constantly challenged by outbreaks of fish diseases, which are difficult to prevent or control. Developing fish strains that are genetically resistant to a disease is a cost-effective and a sustainable solution to address this challenge. To do so, heritable genetic variation in disease resistance should be identified and combined together with other desirable production traits. Aquaculture of common carp has suffered substantial losses from the infectious disease caused by the cyprinid herpes virus type 3 (CyHV-3) virus and the global spread of outbreaks indicates that many cultured strains are susceptible. In this research, CyHV-3 resistance from the feral strain “Amur Sassan” was successfully introgressed into two susceptible cultured strains up to the first backcross (BC1) generation. Variation in resistance of families from F1 and BC1 generations was significantly greater compared to that among families of any of the susceptible parental lines, a good starting point for a family selection program. Considerable additive genetic variation was found for CyHV-3 resistance. This phenotype was transferable between generations with contributions to resistance from both the resistant feral and the susceptible cultured strains. Reduced scale coverage (mirror phenotype) is desirable and common in cultured strains, but so far, cultured mirror carp strains were found to be susceptible. Here, using BC1 families ranging from susceptible to resistant, no differences in resistance levels between fully scaled and mirror full-sib groups were found, indicating that CyHV-3 resistance was successfully combined with the desirable mirror phenotype. In addition, the CyHV-3 viral load in tissues throughout the infection of susceptible and resistant fish was followed. Although resistant fish get infected, viral loads in tissues of these fish are significantly lesser than in those of susceptible fish, allowing them to survive the disease. Taken together, in this study we have laid the foundation for breeding CyHV-3-resistant strains and started to address the mechanisms underlying the phenotypic differences in resistance to this disease.

Anti-CyHV-3 effect of fluorescent, tricyclic derivative of acyclovir 6-(4-MeOPh)-TACV in vitro

“…Although there have been several approaches proposed to diminish the consequences of CyHV-3 infection, the problem has not been solved. The costs as well as the advantages and disadvantages of individual approaches have to be considered (1,4,11,23). Oral administration of the anti-CyHV-3 remedy would be the most convenient treatment that could be applied against CyHV-3.…”

Acyclovir inhibits Cyprinid herpesvirus 3 multiplication in vitro

“…Till now, there have been proposed several approaches to reduce the consequences of the CyHV‐3 infections, such as in vitro CyHV‐3 inhibition with RNAi (Adamek, Rauch, Brogden, & Steinhagen, ; Gotesman, Soliman, Besch, & El‐Matbouli, ), stimulation of the innate immune response (Adamek et al., ), selection of the resistant carp strains (Rakus et al., ; Tadmor‐Levi, Asoulin, Hulata, & David, ) and the vaccination (Boutier et al., ; Perelberg, Ronen, Hutoran, Smith, & Kotler, ; Ronen et al., ). All these solutions have advantages and disadvantages to their applicability.…”

“…, stimulation of the innate immune response , selection of the resistant carp strains (Rakus et al, 2009;Tadmor-Levi, Asoulin, Hulata, & David, 2017) and the vaccination (Boutier et al, 2015;Perelberg, Ronen, Hutoran, Smith, & Kotler, 2005;Ronen et al, 2003). All these solutions have advantages and disadvantages to their applicability.…”

Different transcriptional response between susceptible and resistant common carp (Cyprinus carpio) fish hints on the mechanism of CyHV-3 disease resistance

“…All families were produced and reared in our fish facility. To obtain samples for RNA-Seq, 20-50 naïve fish from each of the six families, with a mean weight of 30-50 grams, were infected using our established cohabitation disease challenge model [18]. On day 0 pre-infection and day 2, 4 and 8 post-infection, three fish from each family were euthanized and spleen tissue samples were quickly collected on ice and immediately stored in RNAlater.…”

“…On day 0 pre-infection and day 2, 4 and 8 post-infection, three fish from each family were euthanized and spleen tissue samples were quickly collected on ice and immediately stored in RNAlater. After day 8 sampling, remaining unsampled fish were left in the cohabitation challenge to verify that the mortalities of families were as expected from the previous measurements done in [18]. The effectiveness of the challenge was monitored also by including susceptible koi fish as controls.…”