Durable Protection from Herpes Simplex Virus-2 Transmission Following Intravaginal Application of siRNAs Targeting Both a Viral and Host Gene

Abstract

Summary A vaginal microbicide should prevent pathogen transmission without disrupting tissue barriers to infection. Ideally it would not need to be applied immediately before sexual intercourse, when compliance is a problem. Intravaginal administration of small interfering RNA (siRNA) lipoplexes targeting Herpes Simplex Virus Type 2 (HSV-2) genes protects mice from HSV-2. However, protection is short-lived and the transfection lipid on its own unacceptably enhances transmission. Here we show that cholesterol-conjugated (chol)-siRNAs without lipid silence gene expression in the vagina without causing inflammation or inducing interferons. A viral siRNA prevents transmission within a day of challenge, whereas an siRNA targeting nectin-1, an HSV-2 receptor, protects for a week, but protection is delayed for a few days until the receptor is down-modulated. Combining siRNAs targeting a viral and host gene protects mice from HSV-2 for a week, irrespective of the time of challenge. Therefore, intravaginal siRNAs could provide sustained protection against viral transmission.

Special delivery: targeted therapy with small RNAs

“…The female genital mucosa can be very efficiently transfected, providing impressive protection against sexual transmission of herpes virus infection, using either siRNAs lipoplexed with cationic lipids or cholesterolconjugated siRNAs. 7,28 Although the lipoplexed siRNA causes mild inflammation, cholesterol-conjugated siRNAs show no evidence of cytotoxicity, inflammation or immune activation. Treatment of diseases that are localized and involve accessible and relatively easily transfected tissues would seem to be the low-hanging fruit for developing RNAi-based therapeutics.…”

Regulation of ovulatory genes in bovine granulosa cells: lessons from siRNA silencing of PTGS2

“…Under in vivo conditions transfection reagents may exhibit immunostimulatory effects and toxicity (Dass 2004). Conjugation of cholesterol, a lipophilic molecule, with siRNA can facilitate the entry of siRNA without the need of transfection reagent (Yuan et al 2008, Medvedeva et al 2009, Wu et al 2009). Chol-PTGS2 siRNA can be therefore used in various cell types expressing PTGS2.…”

Structure - Functions Relations in Small Interfering RNAs

“…In order to achieve in vivo both the efficient cellular uptake and their high nuclease resistance, the 2'-O-Me-modified or/and PS-modified siRNAs conjugated with cholesterol were used [57,151]. In order to increase the thermoasymmetry of the duplex, the nucleotide analogs with opposite effect on the siRNA thermostability can be used simultaneously.…”