Antiviral activity of Viracea® against acyclovir susceptible and acyclovir resistant strains of herpes simplex virus

Abstract

Viracea, a topical microbicide, is a blend of benzalkonium chloride and phytochemicals derived from Echinacea purpurea and is a proprietary formula from Destiny BioMediX Corp. Viracea was tested against 40 strains of herpes simplex virus (HSV): 15 strains (five HSV-1 and ten HSV-2) were resistant to acyclovir (ACV-R) and 25 strains (13 HSV-1 and 12 HSV-2) were susceptible to ACV (ACV-S). The median ED50 of Viracea for the five ACV-R strains of HSV-1 was a 1:100 dilution of the drug with a range of 1:50–1:400. The median ED50 of Viracea for the ten ACV-R strains of HSV-2 was 1:200 with a range of 1:50–1:3200. For the ACV-S strains of HSV-1 and HSV-2, the median ED50 of Viracea was 1:100 and 1:200, respectively. The cytotoxicity of Viracea was evaluated in a standard neutral red dye uptake assay in human foreskin fibroblasts. The cytotoxicity of Viracea approached only 50% at the highest concentration of the drug tested, a 1:2 dilution, indicating that Viracea is non-toxic in this cell cytotoxicity assay. Although the active component(s) in Viracea that has anti-HSV activity is not known, it appears that this extract has good antiviral activity against both ACV resistant and ACV susceptible strains of HSV-1 and HSV-2.