**3.5 Antisense therapy for infectious diseases**

Various antisense mechanisms can be utilized to inhibit viral replication—for example, by binding to viral mRNA to block the translation of the protein or to degrade the viral RNA through an RNase mechanism or by blocking host microR-NAs that support viral replication [6]. Several antisense therapies are currently undergoing clinical trials for various infectious diseases. MicroRNA-122 (miR-122) is highly abundant in the liver and is essential to the stability and propagation of hepatitis C virus (HCV) [32]. This mRNA binds to a highly conserved 5′ untranslated region of the HCV genome, protecting it from degradation and host innate immune responses [32]. Additionally, miR-122 is also believed to play a major role in inflammatory activity in the liver [33], and RG-101, a GalNAc-conjugated oligonucleotide drug, is designed to inhibit miR-122 and HCV replication. The results from this clinical trial were very encouraging and support continued study of the drug.
