Woodchuck hepatitis virus core antigen-based DNA and protein vaccines induce qualitatively different immune responses that affect T cell recall responses and antiviral effects

PreS1 Containing HBc VLPs for the Development of a Combined Therapeutic/Prophylactic Hepatitis B Vaccine

The available HBV vaccines based on the HBV surface protein are manufactured in yeasts and demonstrate excellent prophylactic but no therapeutic activity and are thus ineffective against chronic HBV infection. Five different HBV core proteins (HBc)-full length and C-terminally truncated-were used for the insertion of the short, preS1,aa 20-47 and long, preS1phil, aa 12-60 + 89-119 fragments. Modified virus-like particles (VLPs) were compared for their biotechnological and immunological properties. The expression level of HBc-preS1 proteins was high for all investigated proteins, allowing us to obtain 10-20 mg of purified VLPs from a gram of biomass with the combination of gel filtration and ion-exchange chromatography to reach approximately 90% purity of target proteins. The immunogenicity of chimeric VLPs was tested in BALB/c mice, showing a high anti-preS1 response and substantial T-cell proliferation after stimulation with HBc protein. Targeted incorporation of oligonucleotide ODN 1668 in modified HBc-preS1 VLPs was demonstrated.

Hydrodynamic Delivery: Characteristics, Applications, and Technological Advances

The principle of hydrodynamic delivery was initially used to develop a method for the delivery of plasmids into mouse hepatocytes through tail vein injection and has been expanded for use in the delivery of various biologically active materials to cells in various organs in a variety of animal species through systemic or local injection, resulting in significant advances in new applications and technological development. The development of regional hydrodynamic delivery directly supports successful gene delivery in large animals, including humans. This review summarizes the fundamentals of hydrodynamic delivery and the progress that has been made in its application. Recent progress in this field offers tantalizing prospects for the development of a new generation of technologies for broader application of hydrodynamic delivery.

A novel therapeutic HBV vaccine candidate induces strong polyfunctional cytotoxic T cell responses in mice

BACKGROUND & AIMS

Current standard-of-care suppresses HBV replication, but does not lead to a functional cure. Treatment aiming to cure chronic hepatitis B (CHB) is believed to require the induction of strong cellular immune responses, such as by therapeutic vaccination.

METHODS

We designed a therapeutic HBV vaccine candidate (YF17D/HBc-C) using yellow fever vaccine YF17D as a live-attenuated vector to express HBV core antigen (HBc). Its ability to induce potent cellular immune responses was assessed in a mouse model that supports flavivirus replication.

RESULTS

Following a HBc protein prime, a booster of YF17D/HBc-C was found to induce vigorous cytotoxic T cell responses. In a direct head-to-head comparison, these HBc-specific responses exceeded those elicited by adenovirus-vectored HBc. Target-specific T cells were not only more abundant, but also showed a higher degree of polyfunctionality, with HBc-specific CD8+ T cells producing interferon γ and tumour necrosis factor α in addition to granzyme B. This immune phenotype translated into a superior cytotoxic effector activity toward HBc-positive cells in YF17D/HBc-C vaccinated animals in vivo.

CONCLUSIONS

The results presented here show the potential of YF17D/HBc-C as a vaccine candidate to treat CHB, and warrant follow-up studies in preclinical animal models of HBV persistence in which other candidate vaccines have been unable to achieve a sustained virologic response.

LAY SUMMARY

Resolution of CHB requires the induction of strong cellular immune responses. We used the yellow fever vaccine as a vector for HBV antigens and show that it is capable of inducing high levels of HBV-specific T cells that produce multiple cytokines simultaneously and are cytotoxic in vivo.

TLR2 Stimulation Increases Cellular Metabolism in CD8+ T Cells and Thereby Enhances CD8+ T Cell Activation, Function, and Antiviral Activity

TLR2 serves as a costimulatory molecule on activated T cells. However, it is unknown how the functionality and antiviral activity of CD8⁺ T cells are modulated by direct TLR2 signaling. In this study, we looked at the TLR2-mediated enhancement of TCR-driven CD8⁺ T cell activation in vitro and in woodchuck hepatitis virus transgenic mice. In vitro stimulation of CD8⁺ T cells purified from C57BL/6 mice showed that TLR2 agonist Pam3CSK4 directly enhanced the TCR-dependent CD8⁺ T cell activation. Transcriptome analysis revealed that TLR2 signaling increased expression of bioenergy metabolism-related genes in CD8⁺ T cells, such as IRF4, leading to improved glycolysis and glutaminolysis. This was associated with the upregulation of genes related to immune regulation and functions such as T-bet and IFN-γ. Glycolysis and glutaminolysis were in turn essential for the TLR2-mediated enhancement of T cell activation. Administration of TLR2 agonist Pam3CSK4 promoted the expansion and functionality of vaccine-primed, Ag-specific CD8⁺ T cells in both wild type and transgenic mice and improved viral suppression. Thus, TLR2 could promote CD8⁺ T cell immunity through regulating the energy metabolism.

Vaccine-induced gastric CD4+ tissue-resident memory T cells proliferate in situ to amplify immune response against Helicobacter pylori insult

BACKGROUND

Tissue-resident memory T cells accelerate the clearance of pathogens during recall response. However, whether CD4⁺ TRM cells themselves can provide gastric immunity is unclear.

MATERIALS AND METHODS

We established a parabiosis model between the enhanced green fluorescent protein and wild-type mice that the circulation system was shared, and the wild-type partner was vaccinated with H pylori vaccine composed of CCF and silk fibroin in gastric subserous layer to induce gastric EGFP⁺ CD4⁺ TRM cells. Antigen-specific EGFP⁺ CD4⁺ T cells and proliferous TRM cells were analyzed by flow cytometry. The colonization of H pylori was detected by quantitative real-time PCR. EGFP⁺ CD4⁺ TRM cells and the inflammation of the stomach were observed by histology.

RESULTS

A parabiosis animal model was employed to identify the cells that introduced by vaccination in GSL. Antigen-specific EGFP⁺ CD4⁺ T cells could be detected at day 7 post-vaccination. Thirty days later, EGFP⁺ CD4⁺ TRM cells were established with a phenotype of CD69⁺ CD103^- . Of note, we found that when circulating lymphocytes were depleted by FTY720 administration, these TRM cells could proliferate in situ and differentiate into effector Th1 cells after H pylori challenge. A decrease in H pylori colonization was observed in the vaccinated mice but not unvaccinated mice. Further, we found that although FTY720 was administrated, mounted pro-inflammatory myeloid cells still emerged in the stomach of the vaccinated mice, which might contribute to the reduction of H pylori colonization.

CONCLUSIONS

Our study reveals that H pylori vaccine-induced CD4⁺ TRM cells can proliferate and differentiate in situ to enhance gastric local immunity during recall response.

Heterologous prime-boost immunization with vesiculovirus-based vectors expressing HBV Core antigen induces CD8+ T cell responses in naïve and persistently infected mice and protects from challenge

Chronic hepatitis B virus (HBV) infections cause more than 800,000 deaths per year and currently approved treatments do not cure the disease. Because a hallmark of acute infection resolution is the presence of functional CD8⁺ T cells to the virus, activation of the immune system with therapeutic vaccines represents a potential approach for treating chronic hepatitis B. In this study, we evaluated the immunogenicity and efficacy of two attenuated vesiculovirus-based platforms expressing HBV Core antigen, the highly attenuated vesicular stomatitis virus (VSV) N4CT1 and a unique vaccine platform [virus-like vesicles (VLV)] that is based on a Semliki Forest virus replicon expressing the VSV glycoprotein. We found that heterologous prime-boost immunization with VLV and N4CT1 induced Core-specific CD8⁺ T cell responses in naïve mice. When immunized mice were later challenged with AAV-HBV, functional Core-specific CD8⁺ T cells were present in the liver, and mice were protected from establishment of persistent infection. In contrast, when mice with pre-established persistent HBV replication received prime-boost immunization, functional Core-specific CD8⁺ T cells were found in the spleen but not in the liver. These results highlight the importance of investigating the therapeutic value of different HBV antigens alone and in combination using preclinical animal models, and understanding the correlation between anti-HBV efficacy in these models with human infection.

A Highly Attenuated Vesicular Stomatitis Virus-Based Vaccine Platform Controls Hepatitis B Virus Replication in Mouse Models of Hepatitis B

Therapeutic vaccines may be an important component of a treatment regimen for curing chronic hepatitis B virus (HBV) infection. We previously demonstrated that recombinant wild-type vesicular stomatitis virus (VSV) expressing the HBV middle surface glycoprotein (MHBs) elicits functional immune responses in mouse models of HBV replication. However, VSV has some undesirable pathogenic properties, and the use of this platform in humans requires further viral attenuation. We therefore generated a highly attenuated VSV that expresses MHBs and contains two attenuating mutations. This vector was evaluated for immunogenicity, pathogenesis, and anti-HBV function in mice. Compared to wild-type VSV, the highly attenuated virus displayed markedly reduced pathogenesis but induced similar MHBs-specific CD8⁺ T cell and antibody responses. The CD8⁺ T cell responses elicited by this vector in naive mice prevented HBV replication in animals that were later challenged by hydrodynamic injection or transduction with adeno-associated virus encoding the HBV genome (AAV-HBV). In mice in which persistent HBV replication was first established by AAV-HBV transduction, subsequent immunization with the attenuated VSV induced MHBs-specific CD8⁺ T cell responses that corresponded with reductions in serum and liver HBV antigens and nucleic acids. HBV control was associated with an increase in the frequency of intrahepatic HBV-specific CD8⁺ T cells and a transient elevation in serum alanine aminotransferase activity. The ability of VSV to induce a robust multispecific T cell response that controls HBV replication combined with the improved safety profile of the highly attenuated vector suggests that this platform offers a new approach for HBV therapeutic vaccination.IMPORTANCE A curative treatment for chronic hepatitis B must eliminate the virus from the liver, but current antiviral therapies typically fail to do so. Immune-mediated resolution of infection occurs in a small fraction of chronic HBV patients, which suggests the potential efficacy of therapeutic strategies that boost the patient's own immune response to the virus. We modified a safe form of VSV to express an immunogenic HBV protein and evaluated the efficacy of this vector in the prevention and treatment of HBV infection in mouse models. Our results show that this vector elicits HBV-specific immune responses that prevent the establishment of HBV infection and reduce viral proteins in the serum and viral DNA/RNA in the liver of mice with persistent HBV replication. These findings suggest that highly attenuated and safe virus-based vaccine platforms have the potential to be utilized for the development of an effective therapeutic vaccine against chronic HBV infection.

OFF–ON nanodiamond drug platform for targeted cancer imaging and therapy

The pH-responsive drug delivery system (NPGD) can act as a direct OFF–ON mechanism for activatable bioimaging and cancer therapy.

Toxic adjuvants alter the function and phenotype of dendritic cells to initiate adaptive immune responses induced by oral Helicobacter pylori vaccines

BACKGROUND

Toxic adjuvant is considered as an indispensable constituent for oral Helicobacter pylori (H. pylori) vaccines. However, the elaborate role of toxic adjuvant in the initiation of adaptive immune response is largely undescribed.

MATERIALS AND METHODS

We employed an acid-resistant HP55/PLGA nanoparticles (NPs) delivery system encapsulating three antigens (Hsp, Nap, and Lpp20) from H. pylori and accompanied with three adjuvants (LPS, CpG, and chimeric flagellum (CF)) to explore the underlying mechanism of the adjuvant constituent. H. pylori-specific antibody responses were detected by ELISA. Gastric inflammatory and Th1/Th17 responses were analyzed by flow cytometry. Expressions of inflammatory cytokines were measured by quantitative real-time PCR.

RESULTS

In bone marrow-derived dendritic cells' (BMDCs) model, the addition of toxic adjuvants is responsible for the proinflammatory function, but not the mature phenotype of BMDCs. In vivo, intestinal loop injection with NPs + LPS, rather than NPs alone, altered the dendritic cell (DC) phenotypes in mesenteric lymph nodes and drove a local proinflammatory microenvironment. In a prophylactic vaccination model, mice immunized with NPs + adjuvants significantly reduced the gastric colonization of H. pylori, induced antigen-specific antibody responses and Th1/Th17 cell responses. After H. pylori challenge, these mice showed potent recall responses involving both neutrophil and inflammatory monocyte infiltration. Additionally, TLR4 knockout mice were immunized with NPs + LPS and NPs + CF, respectively; only the recipients of NPs + CF orchestrated a protective response to control bacterial infection.

CONCLUSIONS

Our study indicated that toxic adjuvants within oral H.pylori vaccines altered the function and phenotype of dendritic cells and facilitated the establishment of proinflammatory microenvironment to initiate adaptive immune responses.

MITA/STING and Its Alternative Splicing Isoform MRP Restrict Hepatitis B Virus Replication

An efficient clearance of hepatitis B virus (HBV) requires the coordinated work of both the innate and adaptive immune responses. MITA/STING, an adapter protein of the innate immune signaling pathways, plays a key role in regulating innate and adaptive immune responses to DNA virus infection. Previously, we identified an alternatively spliced isoform of MITA/STING, called MITA-related protein (MRP), and found that MRP could specifically block MITA-mediated interferon (IFN) induction while retaining the ability to activate NF-κB. Here, we asked whether MITA/STING and MRP were able to control the HBV replication. Both MITA/STING and MRP significantly inhibited HBV replication in vitro. MITA overexpression stimulated IRF3-IFN pathway; while MRP overexpression activated NF-κB pathway, suggesting these two isoforms may inhibit HBV replication through different ways. Using a hydrodynamic injection (HI) mouse model, we found that HBV replication was reduced following MITA/STING and MRP expression vectors in mice and was enhanced by the knockout of MITA/STING (MITA/STING^-/-). The HBV specific humoral and CD8⁺ T cell responses were impaired in MITA/STING deficient mice, suggesting the participation of MITA/STING in the initiation of host adaptive immune responses. In summary, our data suggest that MITA/STING and MRP contribute to HBV control via modulation of the innate and adaptive responses.

Smart pH-responsive and high doxorubicin loading nanodiamond for in vivo selective targeting, imaging, and enhancement of anticancer therapy

We introduce a simple and effective strategy to design a promising drug delivery platform for improving the biomedical applications of smart nanodiamond carriers.

Persistence of the recombinant genomes of woodchuck hepatitis virus in the mouse model

Hydrodynamic injection (HI) with a replication competent hepatitis B virus (HBV) genome may lead to transient or prolonged HBV replication in mice. However, the prolonged HBV persistence after HI depends on the specific backbone of the vector carrying HBV genome and the genetic background of the mouse strain. We asked whether a genetically closely related hepadnavirus, woodchuck hepatitis virus (WHV), may maintain the gene expression and replication in the mouse liver after HI. Interestingly, we found that HI of pBS-WHV1.3 containing a 1.3 fold overlength WHV genome in BALB/c mouse led to the long presence of WHV DNA and WHV proteins expression in the mouse liver. Thus, we asked whether WHV genome carrying foreign DNA sequences could maintain the long term gene expression and persistence. For this purpose, the coding region of HBV surface antigen (HBsAg) was inserted into the WHV genome to replace the corresponding region. Three recombinant WHV-HBV genomes were constructed with the replacement with HBsAg a-determinant, major HBsAg, and middle HBsAg. Serum HBsAg, viral DNA, hepatic WHV protein expression, and viral replication intermediates were detected in mice after HI with recombinant genomes. Similarly, the recombinant genomes could persist for a prolonged period of time up to 45 weeks in mice. WHV and recombinant WHV-HBV genomes did not trigger effective antibody and T-cell responses to viral proteins. The ability of recombinant WHV constructs to persist in mice is an interesting aspect for the future investigation and may be explored for in vivo gene transfer.