Complete Viral Clearance Research Articles

The analysis of HPV integration sites based on nanopore sequencing and the profiling changes along the course of photodynamic therapy

ObjectiveTo detect the HPV genotype and integration sites in patients with high-risk HPV infection at different stages of photodynamic therapy using nanopore technology and to evaluate the treatment effect.MethodsFour patients with HPV infection were selected and subjected to photodynamic therapy, and cervical exfoliated cell was sampled at before treatment, after three courses of treatment and six courses of treatment, their viral abundance and insertion sites were analyzed by nanopore technology, and pathological examinations were performed before and after treatment. In this study, we developed a novel assay that combined viral sequence enrichment and Nanopore sequencing for identification of HPV genotype and integration sites at once. The assay has obvious advantages over qPCR or NGS-based methods, as it has better sensitivity after viral sequences enrichment and can generate long-reads (kb to Mb) for better detection rate of structure variations, moreover, fast turn-around time for real-time viral sequencing and analysis.ResultsThe pathological grade was reduced in all four patients after photodynamic therapy. Virus has been cleared in two cases after treatment, the virus amount reduced after treatment but not completely cleared in one case, and two type viruses were cleared and one type virus persisted after treatment in the last patient with multiple infection. Viral abundance and the number of integration sites were positively correlated. Gene enrichment analysis showed complete viral clearance in 1 patient and 3 patients required follow-up.ConclusionNanopore sequencing can effectively monitor the abundance of HPV viruses and integration sites to show the presence status of viruses, and combined with the results of gene enrichment analysis, the treatment effect can be dynamically assessed.

Safety and efficacy of topical artesunate for the treatment of vulvar intraepithelial neoplasia 2/3

ObjectiveTo evaluate the safety, tolerability, and efficacy of topical artesunate ointment for treatment of biopsy-confirmed Human papillomavirus (HPV)-associated Vulvar intraepithelial neoplasia (VIN) 2/3. MethodsParticipants were enrolled on a prospective, IRB-approved, dose-escalation phase I trial testing either 1, 2 or 3 treatment cycles (5 days), every other week, as applicable. Clinical assessments were completed prior to each dose cycle and included exam and review of adverse event (AE) diary cards. HPV testing and colposcopy was completed at 15 and 28 weeks. AEs were assessed according to CTCAE 4.0 criteria. Complete responders (CR) underwent biopsy of the treated site at the 28-weeks while partial (PR) and non (NR)-responders underwent surgical resection or biopsy and ablation. ResultsFifteen patients consented to and began treatment. Per-protocol assessments were completed in 100% at 15- and 80% at 28-weeks. All patients completed prescribed cycles with no grade 3 or 4 AEs. Vulvovaginal burning/ was the most common AE occurring in 93.3%. AEs were grade 2 in 23.7% and included vulvovaginal pruritus (n = 3), swelling (n = 3) and candidiasis (n = 2). The highest ORR was in the 3-cycle group (88.9% with 55.6% CR). HPV-16 was detected either alone (46.7%) or with other subtypes (33.3%) in 80% of lesions and 5 of 8 (62.5%) with CR had complete viral clearance. ConclusionsTopical artesunate for treatment of high-grade VIN shows high tolerability, low toxicity and evidence for clinical response in this initial small series. The safety and observed responses support further study in a Phase II trial.

Virus discovery in dogs with non-suppurative encephalitis reveals a high incidence of tick-borne encephalitis virus infections in Switzerland.

Viral infections are a frequent cause of disseminated non-suppurative encephalitis in dogs. However, using routine diagnostic methods, the specific virus may remain unknown due to extensive or complete viral clearance or because the virus is unexpected or new. A metatranscriptomics-based approach of combining high-throughput sequencing (HTS) and bioinformatics analysis was used to investigate the viral etiology in archival cases of dogs with non-suppurative encephalitis. In formalin-fixed paraffin embedded (FFPE) brain material from the years 1976 to 2021 a high incidence of tick-borne encephalitis virus (TBEV) was detected. Moreover, canine distemper virus (CDV) was identified without typical demyelinating lesions and canine vesivirus (CaVV) was detected as an unexpected virus associated with non-suppurative encephalitis. We demonstrated the viral presence in brain tissues at the sites of inflammation by immunohistochemistry (IHC) and in situ hybridization (ISH). These results highlight the value of emerging sequencing technologies in veterinary diagnostics and expand our knowledge on the etiologies of encephalitis in dogs.

EFFICACY EVALUATION OF BD ORAL SPRAY ON THE SYMPTOMS AND COURSE OF COVID-19 PATIENTS IN THE CLINICAL HOSPITAL

A prospective randomized, open-label, single-blinded clinical trial was conducted to evaluate the efficacy of BD on the symptoms and course of the disease in patients with moderate and severe Covid-19 in the field hospital. 200 hospitalized patients with Covid-19 diagnosis were enrolled. The patients were randomized into 100 patients in the interventional group (BD group) and 100 in the control group. The BD group patients were treated with BD oral spray in conjunction with standard Covid-19 treatment protocol. The control group patients were treated with standard of care without BD. Patients of the BD group demonstrated a significantly faster improvement in all Covid-19 related symptoms, resulting in a shorter time for complete recovery than the control group. More remarkably, patients in the BD group showed a shorter time for complete viral clearance. The addition of BD to the standard of care protocol also resulted in significant improvement in the restoration of taste and smell and reduction of lung infiltration. The patients in the BD group also exhibited fewer adverse events related to treatment. BD is a simple-to-use, safe, and effective adjunctive treatment for moderate and severe Covid-19 cases. BD might be effective for Covid-19 symptoms.

Persistence of RNA Viruses in the Respiratory Tract: An Overview.

Respiratory RNA viruses are a major cause of acute lower respiratory tract infections and contribute substantially to hospitalization among infants, elderly, and immunocompromised. Complete viral clearance from acute infections is not always achieved, leading to persistence. Certain chronic respiratory diseases like asthma and chronic obstructive pulmonary disease have been associated with persistent infection by human respiratory syncytial virus and human rhinovirus, but it is still not clear whether RNA viruses really establish long-term infections as it has been recognized for DNA viruses as human bocavirus and adenoviruses. Herein, we summarize evidence of RNA virus persistence in the human respiratory tract, as well as in some animal models, to highlight how long-term infections might be related to development and/or maintenance of chronic respiratory symptoms.

Antibody response and intra-host viral evolution after plasma therapy in COVID-19 patients pre-exposed or not to B-cell-depleting agents.

SummaryAdministration of plasma therapy may contribute to viral control and survival of COVID‐19 patients receiving B‐cell‐depleting agents that impair humoral immunity. However, little is known on the impact of anti‐CD20 pre‐exposition on the kinetics of SARS‐CoV‐2‐specific antibodies. Here, we evaluated the relationship between anti‐spike immunoglobulin G (IgG) kinetics and the clinical status or intra‐host viral evolution after plasma therapy in 36 eligible hospitalized COVID‐19 patients, pre‐exposed or not to B‐cell‐depleting treatments. The majority of anti‐CD20 pre‐exposed patients (14/17) showed progressive declines of anti‐spike IgG titres following plasma therapy, contrasting with the 4/19 patients who had not received B‐cell‐depleting agents (p = 0.0006). Patients with antibody decay also depicted prolonged clinical symptoms according to the World Health Organization (WHO) severity classification (p = 0.0267) and SARS‐CoV‐2 viral loads (p = 0.0032) before complete virus clearance. Moreover, they had higher mutation rates than patients able to mount an endogenous humoral response (p = 0.015), including three patients with one to four spike mutations, potentially associated with immune escape. No relevant differences were observed between patients treated with plasma from convalescent and/or mRNA‐vaccinated donors. Our study emphasizes the need for an individualized clinical care and follow‐up in the management of COVID‐19 patients with B‐cell lymphopenia.

Intranasal Immunization with Liposome-Displayed Receptor-Binding Domain Induces Mucosal Immunity and Protection against SARS-CoV-2.

The global pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to efforts in developing effective vaccine approaches. Currently, approved coronavirus disease 2019 (COVID-19) vaccines are administered through an intramuscular (I.M.) route. Here, we show that the SARS-CoV-2 spike (S) glycoprotein receptor-binding domain (RBD), when displayed on immunogenic liposomes, can be intranasally (I.N.) administered, resulting in the production of antigen-specific IgA and antigen-specific cellular responses in the lungs. Following I.N. immunization, antigen-presenting cells of the lungs took up liposomes displaying the RBD. K18 human ACE2-transgenic mice that were immunized I.M or I.N with sub-microgram doses of RBD liposomes and that were then challenged with SARS-CoV-2 had a reduced viral load in the early course of infection, with I.M. achieving complete viral clearance. Nevertheless, both vaccine administration routes led to full protection against lethal viral infection, demonstrating the potential for the further exploration and optimization of I.N immunization with liposome-displayed antigen vaccines.

Potential Mechanisms for Lung Fibrosis Associated with COVID-19 Infection.

Pulmonary fibrosis is a sequalae of SARS-CoV-2 infection that currently lacks effective preventative or therapeutic measures. Post-viral lung fibrosis due to SARS-CoV-2 has been shown to be progressive on selected patients using imaging studies. Persistent infiltration of macrophages and monocytes, a main feature of SARS-CoV-2 pulmonary fibrosis, and long-lived circulating inflammatory monocytes might be driving factors promoting the profibrotic milieu in the lung. The upstream signal (s) that regulates the presence of these immune cells (despite complete viral clearance) remains to be explored. Current data indicate that much of the stimulating signals are localized in the lungs. However, an ongoing low-grade systemic inflammation in long COVID-19 symptoms suggests that certain non-pulmonary regulators such as epigenetic changes in hematopoietic stem cells might be critical to the chronic inflammatory response. Since nearly one-third of the world population have been infected, a timely understanding of the underlying pathogenesis leading to tissue remodeling is required. Herein, we review the potential pathogenic mechanisms driving lung fibrosis following SARS-CoV-2 infection based upon available studies and our preliminary findings.

Robust efficacy and long-lasting humoral immunity induced by a respiratory syncytial virus prefusion F-based nanoparticle vaccine in genetically diverse animal models

Abstract Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children, accounting for 7% of deaths in those less than one year of age. Despite multiple exposures to RSV throughout life, natural infection affords only partial protection and there is currently no licensed vaccine against RSV. We developed a vaccine candidate, RSVNanoVax, composed of polyanhydride nanoparticles encapsulating the RSV prefusion F protein and a CpG1668 adjuvant. To assess the efficacy of RSVNanoVax we utilized two model systems with increased genetic variability, Swiss Webster mice and the cotton rat. Following an intranasal prime-boost vaccination with RSVNanoVax, Swiss Webster mice exhibited robust titers of RSV F-directed IgG antibodies in both the serum and lung tissue that were sustained out to at least 1-year post-vaccination. RSV F-directed IgA was also induced within the lung tissue and nasal passages, suggesting that RSVNanoVax stimulates long-lasting systemic and mucosal antibody responses in outbred mice. Serum antibodies maintained robust neutralizing activity against both RSV A and B virus strains. Following RSV challenge, vaccinated mice exhibited complete viral clearance in the lungs as early as day 2 post-infection. Further studies performed in cotton rats demonstrated that RSVNanoVax conferred protection from both viral replication in the lungs as well as RSV-induced pulmonary immunopathology following viral challenge. Vaccinated cotton rats also exhibited robust titers of RSV F-directed serum antibodies with neutralizing capacity. Overall, RSVNanoVax represents a promising RSV vaccine candidate capable of providing long-term protection and immunity in genetically diverse populations. Supported by grants from NIH (R01 AI124093, T32 CA078586, T32 AI007485)

Measles-based Zika vaccine induces long-term immunity and requires NS1 antibodies to protect the female reproductive tract

Zika virus (ZIKV) can cause devastating effects in the unborn fetus of pregnant women. To develop a candidate vaccine that can protect human fetuses, we generated a panel of live measles vaccine (MV) vectors expressing ZIKV-E and -NS1. Our MV-based ZIKV-E vaccine, MV-E2, protected mice from the non-lethal Zika Asian strain (PRVABC59) and the lethal African strain (MR766) challenge. Despite 100% survival of the MV-E2 mice, however, complete viral clearance was not achieved in the brain and reproductive tract of the lethally challenged mice. We then tested MV-based vaccines that expressed E and NS1 together or separately in two different vaccines. We observed complete clearance of ZIKV from the female reproductive tract and complete fetal protection in the lethal African challenge model in animals that received the dual antigen vaccines. Additionally, MV-E2 and MV-NS1, when administered together, induced durable plasma cell responses. Our findings suggest that NS1 antibodies are required to enhance the protection of ZIKV-E antibodies in the female reproductive tract.

Research Progress on the Mechanism of Persistent Low-Level HBsAg Expression in the Serum of Patients with Chronic HBV Infection.

Among HBV-infected persons, there is a group of people with hepatitis B surface antigen (HBsAg) showing persistently low levels of expression. The production of low-level HBsAg does not mean a good outcome of chronic HBV infection. Patients still have virus replication and sustained liver damage, and they have the potential to transmit the infection. This risk poses a challenge to clinical diagnosis and blood transfusion safety and is a major concern of experts. However, the mechanism behind persistent low-level HBsAg expression in serum is not completely clear, and complete virus clearance by the host is vital. In this review, we summarize the research progress on the mechanism behind low-level expression of HBsAg in patients with chronic HBV infection in recent years.

Antiviral T-Cell Frequencies in a Healthy Population: Reference Values for Evaluating Antiviral Immune Cell Profiles in Immunocompromised Patients

Viral infections and reactivations are major causes of morbidity and mortality after hematopoietic stem cell (HSCT) and solid organ transplantation (SOT) as well as in patients with immunodeficiencies. Latent herpesviruses (e.g., cytomegalovirus, Epstein-Barr virus, and human herpesvirus 6), lytic viruses (e.g., adenovirus), and polyomaviruses (e.g., BK virus, JC virus) can cause severe complications. Antiviral drugs form the mainstay of treatment for viral infections and reactivations after transplantation, but they have side effects and cannot achieve complete viral clearance without prior reconstitution of functional antiviral T-cell immunity. The aim of this study was to establish normal ranges for virus-specific T-cell (VST) frequencies in healthy donors. Such data are needed for better interpretation of VST frequencies observed in immunocompromised patients. Therefore, we measured the frequencies of VSTs against 23 viral protein-derived peptide pools from 11 clinically relevant human viruses in blood from healthy donors (n = 151). Specifically, we determined the VST frequencies by interferon-gamma enzyme-linked immunospot assay and classified their distribution according to age and gender to allow for a more specific evaluation and prediction of antiviral immune responses. The reference values established here provide an invaluable tool for immune response evaluation, intensity of therapeutic drugs and treatment decision-making in immunosuppressed patients. This data should make an important contribution to improving the assessment of immune responses in immunocompromised patients.

Increased circulating levels of High Mobility Group Box 1 (HMGB1) in acute-phase Chikungunya virus infection: Potential disease biomarker.

Chikungunya virus (CHIKV) causes a febrile syndrome with intense and debilitating arthralgia that can persist for several months or years after complete virus clearance. As there is no specific antiviral treatment or vaccine against CHIKV, identification of serological markers that help clinical management of CHIKV patients is urgent. The High Mobility Group Box 1 (HMGB1) protein is secreted to extracellular milieu and triggers an intense inflammatory process by inducing the overexpression of pro-inflammatory cytokines. HMGB1 plays an important role in several virus diseases as well as in rheumatoid arthritis. This study focus on the investigation of HMGB1 serum levels in a sera panel from CHIKV-infected patients in an attempt to assess its potential as a biomarker for chikungunya clinical management. Eighty CHIKV-positive samples and 32 samples from healthy donors were subjected to a quantitative HMGB1 ELISA assay to assess the HMGB1 circulating levels. HMGB1 levels were significantly higher in CHIKV-positive samples (516.12ng/mL, SEM±48.83ng/mL) compared to negative control (31.20ng/mL, SEM±3.24ng/mL, p<0.0001). Circulating levels of HMGB1 persisted elevated during the whole acute-phase of disease and correlated with virus titer (p<0.05). The present study is the first to describe increased serum levels of HMGB1 in CHIKV infection and its positive correlation with virus titer, suggesting its potential use as a biomarker for diagnosis and treatment of chikungunya fever.

Virus filter scalability: Demonstration of consistent viral clearance across laboratory and manufacturing scales

Virus removal filtration processes in biopharmaceutical manufacturing are developed, optimized and validated for viral clearance using laboratory scale filters. Thus, the scalability of these filters is critical for accurately extrapolating filtration performance and reliably extending viral clearance to manufacturing scale. Virus removal filter manufacturers generally validate scalability of filtration performance based on various filtration parameters, and virus removal capability is extended to manufacturing scale filters using inert, size-appropriate particles such as gold nanoparticles to avoid the risks associated with using mammalian viruses in large feed volumes. In this study, we use bacteriophage PP7 as a parvovirus model to directly demonstrate viral clearance on Planova™ BioEX virus removal filters across all scales, including manufacturing scale. Filters with hollow fibers from three spinning series with filter sizes ranging from 0.0003 to 4.0 m2 were tested for virus removal, flux, and protein recovery performance using BSA spiked with PP7. Complete viral clearance was observed across all filter sizes with PP7 LRV of ≥4.7 or higher. Flux and protein recovery were also consistent. These results demonstrate the scalability of filtration performance and consistent virus removal at all sizes, supporting the use of laboratory scale filters to validate viral clearance at manufacturing scales.

A SARS-CoV-2 neutralizing antibody with extensive Spike binding coverage and modified for optimal therapeutic outcomes

COVID-19 pandemic caused by SARS-CoV-2 constitutes a global public health crisis with enormous economic consequences. Monoclonal antibodies against SARS-CoV-2 can provide an important treatment option to fight COVID-19, especially for the most vulnerable populations. In this work, potent antibodies binding to SARS-CoV-2 Spike protein were identified from COVID-19 convalescent patients. Among them, P4A1 interacts directly with and covers majority of the Receptor Binding Motif of the Spike Receptor-Binding Domain, shown by high-resolution complex structure analysis. We further demonstrate the binding and neutralizing activities of P4A1 against wild type and mutant Spike proteins or pseudoviruses. P4A1 was subsequently engineered to reduce the potential risk for Antibody-Dependent Enhancement of infection and to extend its half-life. The engineered antibody exhibits an optimized pharmacokinetic and safety profile, and it results in complete viral clearance in a rhesus monkey model of COVID-19 following a single injection. These data suggest its potential against SARS-CoV-2 related diseases.

Prefusion F-based polyanhydride nanovaccine induces robust humoral and cell-mediated immunity resulting in long-lasting protection against respiratory syncytial virus

Abstract Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children, accounting for 7% of deaths in those less than one year of age and leading to more than $300 million in annual medical costs. As natural exposure to the virus generates insufficient immunity, there is a critical need for a safe and efficacious vaccine to prevent RSV-induced disease. We developed an intranasal vaccine, termed RSVNanoVax, composed of polyanhydride nanoparticles encapsulating the RSV prefusion F protein and a CpG1668 oligodeoxynucleotide adjuvant. RSVNanoVax prime-boost vaccination of BALB/c mice induced RSV F-directed IgG serum antibodies specific for both site 0 and site II on the F protein. Systemic antibodies maintained a robust neutralizing capacity out to at least six months post-vaccination. Vaccination with RSVNanoVax also induced F-directed IgA titers within the lungs and nasal passages as well as lung tissue-resident memory CD4 and CD8 T cells, indicating that the vaccine established both a humoral and cell-mediated immune response within the mucosal tissues. Vaccination with RSVNanoVax resulted in protection from RSV-induced disease out to at least six months post-challenge, as measured by weight loss and pulmonary dysfunction. RSVNanoVax vaccination of outbred Swiss Webster mice also elicited protection from RSV-induced disease, and resulted in complete viral clearance as early as day two after RSV challenge. High RSV F-directed antibody titers were also observed in the serum of outbred mice. Based on the robust immune response and the high level of protection observed in both inbred and outbred populations, our prefusion RSV F nanoparticle formulation represents a promising RSV vaccine candidate.

Post-HSCT graft failure due to refractory human cytomegalovirus successfully treated with haploidentical donor-derived immunoglobulins and stem cell graft infusion: A case report

BackgroundHuman cytomegalovirus (HCMV) remains an important cause of transplant-related morbidity and mortality. The incidence of HCMV recurrence in the donor seronegative (D-)/recipient seropositive (R+) group is significantly higher than in other serostatus combinations as a result of a lack of pre-existing HCMV-specific memory T-lymphocytes in the donor, coupled with the eradication of the recipient's cellular immunity due to the conditioning regimen. Case presentationWe describe the case of an 8-year-old βE-thalassemic girl from Bangladesh who was seropositive for human cytomegalovirus (HCMV) and underwent hematopoietic stem cell transplantation from a HLA-matched, unrelated, HCMV-seronegative donor. Despite administering antiviral prophylaxis with commercial pooled anti-HCMV immunoglobulin (Ig) from day +1, the post-transplant course was complicated by prompt viral reactivation, and foscarnet therapy was initiated. The virus was refractory to treatment, leading rapidly to complete bone marrow failure, and targeted immunotherapy was proposed as a second-line therapy. Hypothesizing that the patient and her relatives may have been exposed to similar HCMV strains, we selected the patient's mother, who presented a high HCMV antibody titer, as the donor of virus strain-specific anti-HCMV Ig and T-lymphocytes. Complete viral clearance was achieved after two transfusions of the mother's plasma. Subsequently, the patient underwent a haploidentical rescue transplant, promptly reaching full hematological recovery. ConclusionThese findings suggest that treatment with virus strain-specific Ig may offer a new therapeutic option for critically ill patients.

Glycopeptides as Potential Interventions for COVID-19.

Coronavirus disease 2019 (COVID-19), an infectious disease that primarily attacks the human pulmonary system, is caused by a viral strain called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The outbreak emerged from Wuhan, China, and later spread throughout the world. Until the first week of May 2020, over 3.7 million cases had been reported worldwide and more than 258,000 had died due to the disease. So far, off label use of various drugs has been tried in many clinical settings, however, at present, there is no vaccine or antiviral treatment for human and animal coronaviruses. Therefore, repurposing of the available drugs may be promising to control emerging infections of SARS-COV2; however, new interventions are likely to require months to years to develop. Glycopeptides, which are active against gram-positive bacteria, have demonstrated significant activity against viral infections including SARS-COV and MERS-COV and have a high resemblance of sequence homology with SARS-COV2. Recent in vitro studies have also shown promising activities of aglycon derivative of glycopeptides and teicoplanin against SARS-COV2. Hydrophobic aglycon derivatives and teicoplanin, with minimal toxicity to human cell lines, inhibit entry and replication of SARS-COV2. These drugs block proteolysis of polyprotein a/b with replicase and transcription domains. Teicoplanin use was associated with complete viral clearance in a cohort of patients with severe COVID-19 symptoms. This review attempts to describe the activity, elucidate the possible mechanisms and potential clinical applications of existing glycopeptides against corona viruses, specifically SARS-COV2.

Influenza A(H1N1)pdm09 infection and viral load analysis in patients with different clinical presentations.

BACKGROUND Influenza viral load (VL) can be a decisive factor in determining the antiviral efficacy in viral clearance.OBJECTIVE This study aimed to evaluate the rate of infection and the role of influenza VL on the clinical spectrum of illnesses among different patient groups attended at a tertiary hospital in Brazil.METHODS Samples were collected from patients presenting acute respiratory infection from 2009 to 2013. Overall, 2262 samples were analysed and distributed into three groups: (i) asymptomatic (AS); (ii) symptomatic outpatients (OP); and (iii) hospitalised patients (HP). VL (expressed in Log10 RNA copies/mL) was calculated through a quantitative real-time one-step reverse transcription-polymerase chain reaction (RT-PCR) assay aimed at the M gene, with human RNAseP target as internal control and normalising gene of threshold cycle values.FINDINGS A total of 162 (7.16%) H1N1pdm09 positive samples were analysed. Patients aged from 0.08 to 77 years old [median ± standard deviation (SD): 12.5 ± 20.54]. Children with 5 to 11 years old presented the highest detection (p < 0.0001). AS patients had the lowest VL, with a significant difference when compared with symptomatic patients (p = 0.0003). A higher VL was observed within two days of disease onset. Ten patients (HP group) received antiviral treatment and were followed up and presented a mean initial VL of 6.64 ± 1.82. A complete viral clearance for 50% of these patients was reached after 12 days of treatment.MAIN CONCLUSIONS It is important to evaluate AS patients as potential spreaders, as viral shedding was still present, even at lower VL. Our results suggest that patients with underlying diseases and severe clinical symptoms may be considered for prolonged viral treatment.

Characterization of IL-21-expressing recombinant hepatitis B virus (HBV) as a therapeutic agent targeting persisting HBV infection

Chronic infection by hepatitis B virus (HBV) is associated with high risks of liver fibrosis, cirrhosis and hepatocellular carcinoma. In mouse models of HBV persistence, interleukin 21 (IL-21) has been identified as a potent inducer of viral clearance. Strict hepatotropism makes recombinant HBV (rHBV) vectors ideal for liver-targeting gene delivery. Previously, we established an rHBV vector termed 5c3c, which is highly replicative by itself, but requires HBV envelope proteins provided in trans to produce virions. 5c3c-based rHBV virions are capable of delivering cargo gene expression driven by HBV Sp1 promoter into infected hepatocytes. In this work, we explore the feasibility of using 5c3c-derived rHBV for liver-specific delivery of IL-21 as treatment of chronic HBV infection.Methods: 5c3c-derived rHBV replicons harboring mouse or human IL-21 genes (termed 5c3c-mIL-21 and 5c3c-hIL-21 respectively) were constructed and then tested for the production of rHBV virions in vitro and in vivo. 5c3c-mIL-21's anti-HBV effects were determined in chronic HBV mouse model. Furthermore, superinfection by rHBV virions was analysed using HBV-infected HepG2/NTCP cells and human liver chimeric mice.Results: 5c3c-mIL-21 and 5c3c-hIL-21 were efficiently replicative and produced enveloped virions when provided with envelope proteins, both in vitro and in vivo. In mouse model of HBV persistence, IL-21 expressed from injected 5c3c-mIL-21 replicon induced complete viral clearance. 5c3c-mIL-21 and 5c3c-hIL-21 virions could infect HepG2/NTCP cells and engender sustained IL-21 expression. Most importantly, IL-21-expressing rHBV virions could superinfect HBV-infected HepG2/NTCP cells and human hepatocytes in human liver chimeric mice, and engender sustained IL-21 expression and rHBV production.Conclusion: These data suggest the high potential of 5c3c-derived IL-21-expressing rHBV as a novel therapeutic against chronic HBV infection.