Swarms of chemically modified antiviral siRNA targeting herpes simplex virus infection in human corneal epithelial cells

Abstract

<p>Herpes simplex virus type 1 (HSV-1) is a common virus of mankind and HSV-1 infections<br>are a significant cause of blindness. The current antiviral treatment of herpes infection relies<br>on acyclovir and related compounds. However, acyclovir resistance emerges especially in<br>the long term prophylactic treatment that is required for prevention of recurrent herpes keratitis.<br>Earlier we have established antiviral siRNA swarms, targeting sequences of essential<br>genes of HSV, as effective means of silencing the replication of HSV <em>in vitro</em> or <em>in vivo</em>. In this<br>study, we show the antiviral efficacy of 2´-fluoro modified antiviral siRNA swarms against<br>HSV-1 in human corneal epithelial cells (HCE). We studied HCE for innate immunity<br>responses to HSV-1, to immunostimulatory cytotoxic double stranded RNA, and to the antiviral<br>siRNA swarms, with or without a viral challenge. The panel of studied innate responses<br>included interferon beta, lambda 1, interferon stimulated gene 54, human myxovirus resistance<br>protein A, human myxovirus resistance protein B, toll-like receptor 3 and interferon<br>kappa. Our results demonstrated that HCE cells are a suitable model to study antiviral RNAi<br>efficacy and safety <em>in vitro</em>. In HCE cells, the antiviral siRNA swarms targeting the HSV<br>UL29 gene and harboring 2´-fluoro modifications, were well tolerated, induced only modest<br>innate immunity responses, and were highly antiviral with more than 99% inhibition of viral<br>release. The antiviral effect of the 2’-fluoro modified swarm was more apparent than that of<br>the unmodified antiviral siRNA swarm. Our results encourage further research <em>in vitro</em> and <em>in<br>vivo</em> on antiviral siRNA swarm therapy of corneal HSV infection, especially with modified<br>siRNA swarms.<br></p>