In vitro Assessment of Antiviral Effect of Natural Compounds on Porcine Epidemic Diarrhea Coronavirus

Abstract

Organic acid and essential oils (EOs), well-known antimicrobials, could also possess antiviral activity, a characteristic which has not been completely addressed up to now. In this study, the effect of two organic acids (formic acid and sodium salt of coconut fatty acid distillates) and two single EO compounds (thymol and cinnamaldehye) was evaluated against porcine epidemic diarrhea virus (PEDV). The concentration used for each compound was established by cytotoxicity assays in Vero cells. The antiviral activity was then evaluated at three multiplicities of infection (MOIs) through visual cytopathic effect (CPE) evaluation and an alamarBlue assay as well as real-time reverse-transcription PCR (RT-qPCR) and viral titration of cell supernatants. Formic acid at at a dose of 1,200 ppm was the only compound which showed antiviral activity, with a weak reduction of CPE caused by PEDV. Through the alamarBlue fluorescence assay, we showed a significant anti-CPE effect of formic acid which could not be observed by using an inverted optical microscope. RT-qPCR and infectivity analysis also showed that formic acid significantly reduced viral RNA and viral titers in a PEDV MOI-dependent manner. Our results suggest that the antiviral activity of formic acid could be associated to its inhibitory effect on viral replication. Further studies are required to explore the anti-PEDV activity of formic acid under field conditions alone or together with other antiviral agents.

Characterization of Planktochlorella nurekis Extracts and Virucidal Activity against a Coronavirus Model, the Murine Coronavirus 3

“…Previous studies have suggested that the antiviral activity against Coronavidae members can be attributed to metabolites such as phytol and polysaccharides [ 69 ], which we did not find in our study. Other researchers have reported a prominent role of organic acids in the viricidal effect, with one of the most prominent metabolites being formic acid, which can inhibit the replication of the porcine epidemic diarrhea virus (PEDV) [ 70 ]. According to the PCA, isobutyric acid was the metabolite with the highest impact on viricidal activity.…”

Pharmacological Applications and Action Mechanisms of Phytochemicals as Alternatives to Antibiotics in Pig Production

“…However, formic acid has no function in any anti-PEDV activity in the early steps of the viral cycle with the only exception of a slight effect of viral inactivation at the lowest PEDV MOI. Formic acid at a dose of only 1,200 ppm can effectively inhibit PEDV replication in Vero cells ( 109 ). However, the combination of essential oil and benzoic acid enhances the degradation of PEDV RNA ( 110 ).…”