Carbonyl J acid derivatives block protein priming of hepadnaviral P protein and DNA-dependent DNA synthesis activity of hepadnaviral nucleocapsids.
Current treatments for chronic hepatitis B are effective in only a fraction of patients. All approved directly antiviral agents are nucleos(t)ide analogs (NAs) that target the DNA polymerase activity of the hepatitis B virus (HBV) P protein; resistance and cross-resistance may limit their long-term applicability. P protein is an unusual reverse transcriptase that initiates reverse transcription by protein priming, by which a Tyr residue in the unique terminal protein domain acts as an acceptor of the first DNA nucleotide. Priming requires P protein binding to the ε stem-loop on the pregenomic RNA (pgRNA) template. This interaction also mediates pgRNA encapsidation and thus provides a particularly attractive target for intervention. Exploiting in vitro priming systems available for duck HBV (DHBV) but not HBV, we demonstrate that naphthylureas of the carbonyl J acid family, in particular KM-1, potently suppress protein priming by targeting P protein and interfering with the formation of P-DHBV ε initiation complexes. Quantitative evaluation revealed a significant increase in complex stability during maturation, yet even primed complexes remained sensitive to KM-1 concentrations below 10 μM. Furthermore, KM-1 inhibited the DNA-dependent DNA polymerase activity of both DHBV and HBV nucleocapsids, including from a lamivudine-resistant variant, directly demonstrating the sensitivity of human HBV to the compound. Activity against viral replication in cells was low, likely due to low intracellular availability. KM-1 is thus not yet a drug candidate, but its distinct mechanism of action suggests that it is a highly useful lead for developing improved, therapeutically applicable derivatives.
University Hospital Freiburg, Department of Internal Medicine II/Molecular Biology, Freiburg, Germany.
Yong-Xiang
YX
Wang
Yu-Mei
YM
Wen
Michael
M
Nassal
D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D002934:Cinnamates / Q000737:chemistry / Q000494:pharmacology*; D004279:DNA, Viral / Q000096:biosynthesis; D024882:Drug Resistance, Viral; D015684:Gene Products, pol / Q000737:chemistry / Q000378:metabolism*; D015613:Hepadnaviridae / Q000187:drug effects* / Q000378:metabolism*; D015611:Hepatitis B Virus, Duck / Q000187:drug effects / Q000378:metabolism; D006515:Hepatitis B virus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008958:Models, Molecular; D009282:Naphthalenesulfonates / Q000737:chemistry / Q000494:pharmacology*; D019251:Nucleocapsid / Q000187:drug effects / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry / Q000378:metabolism
C492431:4-hydroxy-7-((((5-hydroxy-6-((4-cinnamylphenyl)azo)-7-sulfo-2-naphthalenyl)amino)carbonyl)amino)-3-((4-cinnamylphenyl))azo-2-naphthalenesulfonic acid; D000998:Antiviral Agents; D002934:Cinnamates; D004279:DNA, Viral; D015684:Gene Products, pol; D046911:Macromolecular Substances; D009282:Naphthalenesulfonates; C066027:P protein, Hepatitis B virus; D012194:RNA-Directed DNA Polymerase