Topical application of polyethylenimine as a candidate for novel prophylactic therapeutics against genital herpes caused by herpes simplex virus

Herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) cause genital herpes, which can enhance the acquisition of human immunodeficiency virus. The development of anti-HSV agents with novel mechanisms of action is urgently required in the topical therapy of genital herpes. In this study, the in vitro and in vivo anti-HSV effects of Epomin SP-012®, a highly cationic polyethylenimine, were evaluated. When the in vitro antiviral effects of SP-012 were assessed, this compound showed potent activity against HSV-1 and HSV-2. It inhibited the attachment of HSV-2 to host cells and cell-to-cell spread of infection in a concentration-dependent manner and exerted a virucidal effect. No SP-012-resistant HSV-2 was found when the virus was successively passaged in the presence of SP-012. In a mouse genital herpes model, topically administered SP-012 inhibited the progression of the disease caused by HSV infection. These data illustrate that SP-012 may be a novel class of HSV inhibitor that would be acceptable for long-term topical application.