Abundance of G-Quadruplex Forming Sequences in the Hepatitis Delta Virus Genomes
Résumé
Hepatitis Delta virus (HDV) is a unique and highly unusual RNA satellite virus that depends on the presence of the hepatitis B virus (HBV) to be infectious. Its single-stranded RNA genome is very compact and variable, consisting of eight major genotypes distributed unequally on various continents. The significance of noncanonical secondary structures in DNA or RNA, such as G-quadruplexes (G4s), is becoming more evident especially for transcription, replication, and translation. G4s are formed from guanine-rich sequences and have been found in most eukaryotic and prokaryotic genomes, as well as viruses. In this study, we analyzed the G-quadruplex propensity of HDV genomes using G4Hunter. In contrast to the HBV virus, which has a G4 density similar to that of the human genome, the HDV virus possesses a significantly higher number of potential quadruplex-forming sequences (PQS) with a density more than four times higher than that of the human genome. This observation suggests a crucial role for G-quadruplexes in HDV, particularly because the tracks with the potential to form G-quadruplexes are well conserved. Furthermore, the high prevalence of the G-quadruplex-forming sequence could represent a promising therapeutic target to control HDV replication.