Interaction between Toll-Like Receptor 9-CpG Oligodeoxynucleotides and Hepatitis B Virus Virions Leads to Entry Inhibition in Hepatocytes and Reduction of Alpha Interferon Production by Plasmacytoid Dendritic Cells

Abstract

We previously reported that Toll-like receptor 9 (TLR9)-CpG oligonucleotides could inhibit the establishment of hepatitis B virus (HBV) infections in hepatocytes. Our aim was to uncover the underlying mechanisms of this inhibition. HepaRG cells, RPMI-B lymphoblastoma cells, and primary plasmacytoid dendritic cells (pDCs) exposed to HBV and TLR9 ligands/agonists in various configurations were used. We observed an inhibition of HBV infection upon TLR9 stimulations only when agonist was applied during inoculation. This inhibition was independent of interleukin-6 (IL-6)/interferon-inducible protein 10 (IP-10) production as well as of TLR9 expression in hepatocytes. We further demonstrated an entry inhibition mechanism by showing a noncovalent binding of TLR9 agonist to HBV particles. Besides inhibiting HBV entry into hepatocytes, this biophysical interaction between HBV virions and TLR9 agonist was responsible for a reduction of alpha interferon (IFN-α) expression by pDCs. Interestingly, subviral particles composed of only HBsAg were able to genuinely inhibit the TLR9 pathway, without titrating TLR9 ligands. To conclude, our data suggest that synthetic TLR9-CpG oligonucleotides can strongly inhibit HBV entry by "coating" HBV virions and thereby preventing their interaction with cellular receptor. This titration effect of TLR9 agonist is also artifactually responsible for the inhibition of TLR9 engagement in pDCs, whereas a genuine inhibition of this innate pathway was confirmed with HBsAg subviral particles.

Variants of hepatitis B virus surface antigen observed during therapy with nucleic acid polymer REP 2139‐Ca have no influence on treatment outcome and its detection by diagnostic assays

“…This control seems to be immune‐mediated as a result of reduction in HBsAg. It has been shown that large amounts of HBsAg have immunosuppressive effects in HBV infection and its clearance in the circulation establishes a more permissive immunological environment where functional control can be restored. Recent results indicate that REP 2139 exposure has no direct immunostimulatory properties .…”

Toll-like receptor dual-acting agonists are potent inducers of PBMC-produced cytokines that inhibit hepatitis B virus production in primary human hepatocytes

“…Among agonists of pattern recognizing receptors expressed in primary liver cells 25 , namely agonists of Toll-like receptors (TLRs) attracted interest because of their potency to induce IFNs and proinflammatory cytokines and chemokines in both hepatocytes and non-parenchymal cells 23 , 24 . Moreover, it was shown that GS-9620 (vesatolimod), an agonist of endosomal TLR7, which is preferentially expressed in plasmacytoid dendritic cells (pDCs) 26 – 30 but not in primary hepatocytes (PHH) 23 , 31 , 32 , significantly reduced viremia and cccDNA expression, and led to functional cure in animal models 20 – 22 . A recent study showed that TLR1/2 and TLR3 ligands inhibit HBV replication in PHH, and that the same ligands also induce the production of antiviral cytokines in peripheral blood mononuclear cells (PBMCs) 23 .…”

Development of antiviral drugs against hepatitis B virus

“…CpG寡脱氧核苷酸是TLR9激动剂, 其处理浆细胞样树 突状细胞(plasmacytoid dendritic cell, pDC)和B细胞后 可以诱导IFN-α的产生 [142] . 用CpG 21798与恩替卡韦…”