CpG oligodeoxynucleotide inhibits HBV replication in a hydrodynamic injection murine model

Long-term and efficient inhibition of hepatitis B virus replication by AAV8-delivered artificial microRNAs

Chronic hepatitis B virus (HBV) infection remains a global health problem and current treatments are insufficient due to immune tolerance to hepatitis B surface antigen (HBsAg). RNA interference (RNAi) is a more promising approach for antiviral therapy. Here, 17 single artificial microRNAs (amiRNAs) targeting the highly conserved regions of HBV genome were screened to inhibit HBV replication. In addition, we compared three tandem amiRNAs, each containing 3 different amiRNAs, out of which amiRNA135 was selected to be studied in detail. In vitro data showed that amiRNA135 significantly inhibited the replication of different HBV genotypes (including resistant and mutant). In vivo study was carried out by adeno-associated virus 8-mediated gene delivery, we found that the anti-HBV effects of AAV8-amiRNA135 were time and dose-dependent. Serum HBsAg and HBeAg in high dose groups were significantly reduced at 7 days after a single intravenous vector injection, and maintained at low levels throughout a 15-month experiment. Immunohistochemical staining and HBV core particle DNA analysis confirmed that HBV replication in the liver was strongly inhibited by AAV8-amiRNA135. Taken together, our data suggest that AAV8-mediated trimeric amiRNA expression is a promising therapeutic approach for chronic HBV infection.

CpG-C ODN M362 as an immunoadjuvant for HBV therapeutic vaccine reverses the systemic tolerance against HBV

Chronic Hepatitis B virus (CHB) infection is a global public health problem. Oligodeoxynucleotides (ODNs) containing class C unmethylated cytosine-guanine dinucleotide (CpG-C) motifs may provide potential adjuvants for the immunotherapeutic strategy against CHB, since CpG-C ODNs stimulate both B cell and dendritic cell (DC) activation. However, the efficacy of CpG-C ODN as an anti-HBV vaccine adjuvant remains unclear. In this study, we demonstrated that CpG M362 (CpG-C ODN) as an adjuvant in anti-HBV vaccine (cHBV-vaccine) successfully and safely eliminated the virus in HBV-carrier mice. The cHBV-vaccine enhanced DC maturation both in vivo and in vitro, overcame immune tolerance, and recovered exhausted T cells in HBV-carrier mice. Furthermore, the cHBV-vaccine elicited robust hepatic HBV-specific CD8⁺ and CD4⁺ T cell responses, with increased cellular proliferation and IFN-γ secretion. Additionally, the cHBV-vaccine invoked a long-lasting follicular CXCR5⁺ CD8⁺ T cell response following HBV re-challenge. Taken together, CpG M362 in combination with rHBVvac cleared persistent HBV and achieved long-term virological control, making it a promising candidate for treating CHB.

Enrichment of Ly6Chi monocytes by multiple GM-CSF injections with HBV vaccine contributes to viral clearance in a HBV mouse model

Adjuvants are considered a necessary component for HBV therapeutic vaccines but few are licensed in clinical practice due to concerns about safety or efficiency. In our recent study, we established that a combination protocol of 3-day pretreatments with GM-CSF before a vaccination (3 × GM-CSF+VACCINE) into the same injection site could break immune tolerance and cause over 90% reduction of HBsAg level in the HBsAg transgenic mouse model. Herein, we further investigated the therapeutic potential of the combination in AAV8–1.3HBV-infected mice. After 4 vaccinations, both serum HBeAg and HBsAg were cleared and there was a 95% reduction of HBV-positive hepatocytes, in addition to the presence of large number of infiltrating CD8⁺ T cells in the livers. Mechanistically, the HBV-specific T-cell responses were elicited via a 3 × GM-CSF+VACCINE-induced conversion of CCR2-dependent CD11b⁺ Ly6C^hi monocytes into CD11b⁺CD11c⁺ DCs. Experimental depletion of Ly6C^hi monocytes resulted in a defective HBV-specific immune response thereby abrogating HBV eradication. This vaccination strategy could lead to development of an effective therapeutic protocol against chronic HBV in infected patients.