Viral RNA (Replicon) (RepRNA)

The replicon RNA phosphate backbone is the structural scaffold of a self-replicating RNA molecule, typically derived from viral genomes such as those of the Hepatitis C virus (HCV) or alphaviruses. It consists of a repeating chain of ribose sugars and phosphate groups linked by phosphodiester bonds, providing the necessary framework for the viral genetic code and its replication. In therapeutic contexts, this backbone is a primary target for antiviral agents; nucleoside and nucleotide analogs like remdesivir and sofosbuvir are incorporated into the growing RNA strand by viral polymerases, leading to chain termination or the accumulation of deleterious mutations. Furthermore, the backbone's negative charge facilitates essential interactions with cationic proteins, such as the viral nucleocapsid protein, and small molecules that stabilize the replication complex. Modern therapeutic strategies also utilize the backbone as a target for sequence-specific cleavage by RNA interference (RNAi) or antisense technologies, effectively halting viral protein production and genome amplification. Additionally, the backbone is a key component in the design of self-amplifying RNA (saRNA) vaccines, where it must be protected from degradation by host RNases to ensure sustained antigen expression.

Other names

Replicon RNAViral RNA phosphate backboneSelf-amplifying RNAsaRNAViral genomic RNARNA backbone

Drugs targeting the replicon RNA phosphate backbone primarily act through incorporation as chain terminators (nucleotide analogs), induction of lethal mutagenesis, or direct cleavage of the phosphodiester bonds (siRNAs, ribozymes, and CRISPR-Cas13). Small molecules may also bind electrostatically to the negatively charged phosphate groups to disrupt RNA-protein interactions.