Construction of a recombinant African swine fever virus with firefly luciferase and eGFP reporter genes and its application in high-throughput antiviral drug screening.

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African Swine Fever (ASF) is a highly lethal and contagious disease in pigs caused by African Swine Fever Virus (ASFV), which primarily infects domestic pigs and wild boars, with a mortality rate of up to 100%. Currently, there are no commercially available vaccines or drugs that are both safe and effective against ASFV. The ASFV 0428C strain was continuously passaged in Vero cells, and the adapted ASFV demonstrated efficient replication in Vero cells. The adapted ASFV was used as the parental virus, and an expression cassette encoding a dual reporter gene for firefly luciferase (Fluc) and enhanced green fluorescent protein (eGFP) was inserted into the ASFV genome using CRISPR/Cas9 gene editing technology to construct a recombinant ASFV variant (rASFV-FLuc-eGFP). rASFV-Fluc-eGFP was genetically stable, effectively infected porcine alveolar macrophages (PAM) and Vero cells, and expressed Fluc and eGFP concurrently. This study provides a tool for investigating the infection and pathogenic mechanisms of ASFV, as well as for screening essential host genes and antiviral drugs. Additionally, a high-throughput screening model of antiviral drugs was established based on rASFV-FLuc-eGFP in passaged cells, 218 compounds from the FDA-approved compound library were screened, and 5 candidate compounds with significant inhibitory effects in Vero cells were identified. The inhibitory effects on ASFV were further validated in both Vero and PAM cells, resulting in the identification of Salvianolic acid C (SAC), which demonstrated inhibitory effects and safety in both cell types. SAC is a candidate drug for the prevention and control of ASFV and shows promising application prospects.