Determining anti-betanodavirus compounds through a GF-1 cell-based screening platform

- A grouper fin cell viability assay was used to screen small molecule compounds for anti-betanodavirus properties.
- Forty-three compounds with virus-inhibitory properties were identified.
- Proadifen hydrochloride inhibited viral RNA by 99.68% 5 days post-infection.
- 18 monoamine neurotransmitter agents were found to inhibit betanodavirus-induced cell death.

Betanodavirus is a highly contagious pathogen, responsible for severe losses incurred in the aquaculture industry. Currently, there are no commercially available antivirals against the virulence observed during very early stages of fish larvae development. Therefore, we developed a novel GF-1 (grouper fin cell) cell viability-based screening assay to facilitate the discovery of an anti-betanodavirus agent. The assay conditions were optimized and the robustness of the assay was confirmed by a Z′ factor value ranging from 0.7 to 0.94. After screening a library of 2000 small molecule compounds, 43 compounds with a virus inhibition capacity of ⩾55% were identified. A cytochrome P450 inhibitor, proadifen hydrochloride, was validated with an EC50 value of 6.48 μM and a CC50 value of 20.63 μM. This compound inhibited the amplification of viral RNA by 99.68% 5 days post-infection. Surprisingly, we found that 18 of 43 compounds act as neurotransmitter agents. These findings indicate a novel way of investigating the infection mechanism of betanodavirus, and suggest potential candidates for an anti-betanodavirus drug.