Contortrostatin, a Homodimeric Disintegrin Isolated from Snake Venom Inhibits Herpes Simplex Virus Entry and Cell Fusion

Background Herpes simplex virus (HSV) causes significant health problems from periodical skin and corneal lesions to encephalitis. HSV entry provides a unique opportunity for therapeutic intervention. In this study, we evaluated contortrostatin (CN), an Arg-Gly-Asp motif containing disintegrin isolated from snake venom, as a novel therapeutic agent with ability to block HSV entry and related membrane fusion. Methods In vitro efficacy of CN against HSV was determined using an HSV type-1 (HSV-1) entry assay based on the measurement of β-galactosidase reporter activity originating from the genome of a recombinant strain of HSV-1(KOS) gL86. HSV-1 glycoprotein-mediated cell-to-cell fusion was used to study the effect of CN on polykaryocyte formation. Primary as well as transformed cell lines were used for this study. Results Pre-treatment of Chinese hamster ovary (CHO-K1) cells expressing HSV-1 glycoprotein D receptors and primary cultures of human corneal fibroblasts (CF) with CN resulted in the inhibition of entry, cell-to-cell fusion, and polykaryocyte formation. Interestingly, a more pronounced anti-HSV-1 effect was observed in naturally susceptible CF than CHO-K1 cells. Conclusions CN, a novel venom-derived peptide, exhibits the ability to block two key steps, entry and cell-to-cell fusion, in HSV infection. Showing strong promise for development as an anti-HSV agent, it also demonstrates better prophylactic efficacy in primary cells.