Thapsigargin inhibition of coronavirus PHEV replication by Ca2+ mediated metabolic reprogramming

The coronaviruses (CoVs) represent a large family of human and animal pathogens that cause significant health and economic burdens worldwide. Porcine hemagglutinating encephalomyelitis virus (PHEV), belonging to the genus Betacoronavirus, is one of the six coronaviruses that infect pigs, for which no effective drug or vaccine is commercially available. Here, we found that thapsigargin (Tg), an ER stress inducer, potently blocks PHEV replication in non-cytotoxic levels and the antiviral effect is long-lasting at least 60 h post-Tg exposure in different cells. Time-of-addition assay demonstrated that Tg significantly inhibit PHEV replication in N2a cells when treated immediately before, during, or after virus infection. Tg does not directly interact with PHEV particles and transcriptome analysis reveals a unique antiviral mechanism of Tg through Ca2+ mediated metabolic reprogramming. Crucially, oral administration of Tg prolong the survival time and reduced virus titres in the brains of treated mice. Besides, Tg also exerts a profound antiviral effect on alphacoronavirus, deltacoronavirus, rhabdoviruses, parapoxvirus and picornavirus. Taken together, Tg exerts antiviral effects by targeting host factors shared by different viruses, suggesting that this compound (or derivatives thereof) may be developed into broad-spectrum antiviral drugs without considering the drug resistance caused by virus mutation.