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

Abstract

Background Infectious disease outbreaks form major setbacks to aquaculture production and to further development of this important sector. Cyprinid herpes virus-3 (CyHV-3) is a dsDNA virus widely hampering production of common carp ( Cyprinus carpio ), one of the most farmed fish species worldwide. Genetically disease resistant strains are highly sought after as a sustainable solution to this problem. To study the genetic basis and cellular pathways underlying disease resistance, RNA-Seq was used to characterize transcriptional responses of susceptible and resistant fish at day 4 after CyHV-3 infection.Results In susceptible fish, over four times more differentially expressed genes were up-regulated between day 0 and 4 compared to resistant fish. Susceptible and resistant fish responded distinctively to infection as only 55 (9%) of the up-regulated genes were shared by these fish types. Susceptible fish elicited earlier a typical anti-viral response, involving interferon and interferon responsive genes. Moreover, chemokine profiles indicated different cellular immunity responses. A comparative phylogenetic approach assisted in gene copies annotation pointing to different orthologous copies common to bony-fishes and even carp-specific paralogs that were differentially regulated and contributed to the different response of these fish types. Susceptible fish up-regulated more ccl19 chemokines, which attract T-cells and macrophages, the anti-viral role of which is established, whereas resistant fish up-regulated more cxcl8/il8 chemokines, which attract neutrophils, the antiviral role of which is unfamiliar.Conclusions Taken together, by pointing out transcriptional differences between susceptible and resistant fish in response to infection, this study unraveled possible genes and pathways that take part in disease resistance mechanisms in fish and thus, enhances our understanding of fish immunogenetics and supports the development of sustainable and safe aquaculture.

Immune responses in carp strains with different susceptibility to carp edema virus disease

“…These genogroups are seemingly selective mutations targeted toward the numerous variants within the common carp strains/species ( Adamek et al, 2017c ). It has been also reported, that there are differences between various strains of carp in the expression of cytokines during viral infections, specifically the interferon (IFN) and interferon-stimulated genes (ISGs) ( Tadmor-Levi et al, 2019 ). Several varieties of common carp have emerged as an outcome of natural geographic separation of common carp groups and domestication, providing a wide range of genetic resources.…”