Researchers at the Institute of Hydrobiology, Chinese Academy of Sciences, have established a highly permissive cell line GiCS derived from the skin tissue of gibel carp (Carassius gibelio). This cell line, along with a novel diagnostic method, offers robust tools for the early detection and study of Carassius auratus herpesvirus (CaHV), according to two studies by the authors published in the KeAi journal Water Biology and Security.

Carassius_gibelio_male_head_2009_G1

Source: George Chernilevsky

Head of a male Carassius gibelio showing lots of epithelial tubercles which appear at spawning time. This fish was caught in the Southern Bug river, Ukraine.

Gibel carp, a popular aquaculture species in China with an annual production exceeding 2.5 million tons, faces significant threats from infectious diseases, particularly those of viral origins. CaHV is known to cause severe gill hemorrhages and high mortality rates in gibel carp. Despite the virus being isolated and sequenced nearly a decade ago, knowledge on its pathogenesis has been limited due to the absence of a suitable cell line for in vitro virus propagation.

Pathway into fish

To that end, the researchers analyzed the pathway for viruses’ entry into a fish. “Understanding the importance of the skin as the primary contact point with pathogens in aquatic environments, we focused on developing a cell line from this tissue, explains Ke Fei, lead authors of the two studies.

The GiCS cell line, characterized by a modal chromosome number of 156, exhibits high susceptibility to CaHV and several other aquatic animal viruses. This marks the first time that CaHV can be stably cultured in vitro.

In addition, a detection method utilizing droplet digital PCR was developed. This method allows for the sensitive detection of CaHV in infected fish on the first day post-infection, with a detection limit of less than 1 copy per microliter.

“The newly established in vitro infection model will significantly benefit and expedite our research on the pathogenesis mechanism of CaHV. It also opens up avenues for developing cell-based vaccines against the virus,” adds Ke. “With the droplet digital PCR method, we can now identify infected fish before clinical symptoms appear, enabling early intervention to prevent disease spread and reduce economic losses.”

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