Nanoparticles encapsulating hepatitis B virus cytosine-phosphate-guanosine induce therapeutic immunity against HBV infection

Abstract

Infection with hepatitis B virus (HBV) is the most common cause of liver disease worldwide. However, because the current interferon (IFN)-based treatments have toxic side effects and marginal efficacy, improved antivirals are essential. Here we report that unmethylated cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODNs) from the HBV genome (HBV-CpG) induced robust expression of IFN-a by plasmacytoid dendritic cells (pDCs) in a Toll-like receptor 9 (TLR9)-dependent manner. We also identified inhibitory guanosine-rich ODNs in the HBV genome (HBV-ODN) that are capable of inhibiting HBV-CpG-induced IFN-a production. Furthermore, nanoparticles containing HBV-CpG, termed NP(HBV-CpG), reversed the HBV-ODN-mediated suppression of IFN-a production and also exerted a strong immunostimulatory effect on lymphocytes. Our results suggest that NP(HBV-CpG) can enhance the immune response to hepatitis B surface antigen (HBsAg) and skew this response toward the Th1 pathway in mice immunized with rHBsAg and NP(HBV-CpG). Moreover, NP(HBV-CpG)-based therapy led to the efficient clearance of HBV and induced an anti-HBsAg response in HBV carrier mice. Conclusion: Endogenous HBV-CpG ODNs from the HBV genome induce IFN-a production so that nanoparticle-encapsulated HBV-CpG may act as an HBsAg vaccine adjuvant and may also represent a potent therapeutic agent for the treatment of chronic HBV infection. (HEPATOLOGY 2014;59:385-394) P ersistent infection with the hepatitis B virus (HBV) affects more than 360 million people worldwide and has become a severe public health problem owing to the increased risk of liver cirrhosis and hepatocellular carcinoma in infected individuals. The current recombinant hepatitis B surface antigen (rHBsAg) vaccine provides protection against HBV infection but fails to protect 10% of those who are vaccinated and is also ineffective for individuals who are already infected with HBV. Conventional antiviral drugs used for the treatment of HBV, including lamivudine and interferon-alpha (IFN-a), suppress viral replication and reduce hepatic symptoms. 1 However, the persistence of HBV covalently closed circular DNA (cccDNA) and defective immune responses lead to treatment failure and progression to liver disease. 2 Therefore, more efficient therapeutic strategies are needed to eradicate HBV infection.HBV seems to avoid inducing strong innate immune responses including the type I IFN response. 2 Therefore, methods of inducing vigorous immune responses against HBV may play a critical role in the clearance of HBV infection. The unmethylated cytosine-phosphate-guanosine (CpG) motifs presented in bacterial DNA can stimulate the immune system by interacting with the pattern-recognition receptor Tolllike receptor 9 (TLR9). 3 TLR9 is predominantly expressed in plasmacytoid dendritic cells (pDCs) and

A MAVS/TICAM-1-Independent Interferon-Inducing Pathway Contributes to Regulation of Hepatitis B Virus Replication in the Mouse Hydrodynamic Injection Model

“…In addition, the number of pDCs has been previously reported to be reduced in vivo during several systemic viral infections including HBV [37]. In one of the most recent reports, Lv et al [38], showed that HBV-derived CpG induces potent IFN-α production by human pDCs, which may partially explain how pDCs interact with HBV in infection. However, the cause of weak participation in the early response of IFN induction in Myd88 -/- mice remains to be determined.…”

Host–virus interactions in hepatitis B and hepatitis C infection

“…In one study, endogenous HBV-CpG oligodeoxynucleotides from the HBV genome stimulated IFN-a production by pDCs in a TLR-9-dependent manner, thus resulting in the clearance of HBV in HBV carrier mice [50]. The importance of TLR9 signaling has also been reported in other mice models where it induced the intrahepatic aggregates of myeloid cells and efficiently supported local proliferation of effector CD8 ?…”

Contribution of Toll-like receptors to the control of hepatitis B virus infection by initiating antiviral innate responses and promoting specific adaptive immune responses

“…Combined with rHBsAg immunization, administration of nanoparticles containing HBV-CpG led to the clearance of HBV and induced an anti-HBsAg response in HBV carrier mice. 64 Along the same lines, Wu et al demonstrated that intrahepatic administration of TLR3 ligand poly(I:C) could recruit CD8 1 T cells into the liver and clear HBV in an IFN-and CXCR3-dependent manner. 65 These studies indicate that TLR agonists may be used as immunomodulatory agents for the treatment of chronic HBV infection by augmenting the HBV-specific T-or B-cell responses.…”