Abstract
Some free fatty acids derived from milk and vegetable oils are known to have potent antiviral and antibacterial properties. However, therapeutic applications of short to medium chain fatty acids are limited by physical characteristics such as immiscibility in aqueous solutions. We evaluated a novel proprietary formulation based on an emulsion of short chain caprylic acid, ViroSAL, for its ability to inhibit a range of viral infections in vitro and in vivo. In vitro, ViroSAL inhibited the enveloped viruses Epstein-Barr, measles, herpes simplex, Zika and orf parapoxvirus, together with Ebola, Lassa, vesicular stomatitis and SARS-CoV-1 pseudoviruses, in a concentration- and time-dependent manner. Evaluation of the components of ViroSAL revealed that caprylic acid was the main antiviral component; however, the ViroSAL formulation significantly inhibited viral entry compared with caprylic acid alone. In vivo, ViroSAL significantly inhibited Zika and Semliki Forest Virus replication in mice following the inoculation of these viruses into mosquito bite sites. In agreement with studies investigating other free fatty acids, ViroSAL had no effect on norovirus, a non-enveloped virus, indicating that its mechanism of action may be via surfactant disruption of the viral envelope. We have identified a novel antiviral formulation that is of great interest for prevention and/or treatment of a broad range of enveloped viruses.
Footnotes
Funding This work was supported by the Thomas O’Hanlon scholarship for veterinary medicine (NF), University College Dublin, Ireland. DB is supported by a UK MRC New Investigator Research Grant (MR/P021735/1).
Conflicts of interest NFF: No conflict; LWM: No conflict; DGC: No conflict; YC: No conflict; DB: No conflict; CSL: no conflict; ET: No conflict; SRB: no conflict; DAL: no conflict; MP: no conflict; CSMcK: no conflict; MAF is a Director of Westgate Biomedical and the inventor of ViroSAL formulations; AWB: no conflict.
Glossary VSV: vesicular stomatitis virus; HSV-1: herpes simplex virus 1; HFF: human foreskin fibroblasts; FBS: foetal bovine serum; FLS: foetal lamb skin cells; gD: glycoprotein D; HIV: human immunodeficiency virus; DMEM: Dulbecco’s Modified Eagle’s Medium; RLU: relative light units; MeV: measles virus; eGFP: enhanced green fluorescent protein; EBV: Epstein-Barr virus; PCR: polymerase chain reaction; PFU: plaque forming units; MNV: murine norovirus; MOI: multiplicity of infection; TCID50: 50% tissue culture infectious dose; SARS-CoV-1: SARS coronavirus 1; SFV: Semliki Forest virus; ZIKV: Zika virus.