Conservation of the HBV RNA element epsilon in nackednaviruses reveals ancient origin of protein-primed reverse transcription
Jürgen Beck, Stefan Seitz, Chris Lauber, Michael Nassal
Abstract
Significance Hepadnaviruses, including hepatitis B virus (HBV) as a major human pathogen, are small, enveloped DNA viruses, which replicate by reverse transcription of an RNA intermediate. Unlike retroviruses, which use tRNA as primer for reverse transcription, hepadnaviruses employ a unique protein-priming mechanism involving de novo synthesis of a DNA primer covalently attached to the viral polymerase. Here, we show that this mechanism is highly conserved on the molecular level in distantly related non-enveloped fish viruses which diverged from ancestral hepadnaviruses more than 400 Mya. The exceptional level of conservation and the absence of known homologous cellular mechanisms renders HBV protein priming a promising, yet unexplored, antiviral target for the development of novel therapeutics against this highly relevant pathogen.