Construction of polyomavirus-derived pseudotype virus-like particles displaying a functionally active neutralizing antibody against hepatitis B virus surface antigen

Background: Virus-like particles (VLPs) can be efficiently produced by heterologous expression of viral structural proteins in yeast. Due to their repetitive structure, VLPs are extensively used for protein engineering and generation of chimeric VLPs with inserted foreign epitopes. Hamster polyomavirus VP1 represents a promising epitope carrier. However, insertion of large sized protein sequences may interfere with its self-assembly competence. The co-expression of polyomavirus capsid protein VP1 with minor capsid protein VP2 or its fusion protein may result in pseudotype VLPs where an intact VP1 protein mediates VLP formation. In the current study, the capacity of VP1 protein to self-assemble to VLPs and interact with the modified VP2 protein has been exploited to generate pseudotype VLPs displaying large-sized antibody molecules. Results: Polyomavirus-derived pseudotype VLPs harbouring a surface-exposed functionally active neutralizing antibody specific to hepatitis B virus (HBV) surface antigen (HBsAg) have been generated. The pseudotype VLPs consisting of an intact hamster polyomavirus (HaPyV) major capsid protein VP1 and minor capsid protein VP2 fused with the anti-HBsAg molecule were efficiently produced in yeast Saccharomyces cerevisiae and purified by density-gradient centrifugation. Formation of VLPs was confirmed by electron microscopy. Two types of pseudotype VLPs were generated harbouring either the single-chain fragment variable (scFv) or Fc-engineered scFv on the VLP surface. The antigen-binding activity of the purified pseudotype VLPs was evaluated by ELISA and virus-neutralization assay on HBV-susceptible primary hepatocytes from Tupaia belangeri. Both types of the pseudotype VLPs were functionally active and showed a potent HBV-neutralizing activity comparable to that of the parental monoclonal antibody. The VP2-fused scFv molecules were incorporated into the VLPs with higher efficiency as compared to the VP2-fused Fc-scFv. However, the pseudotype VLPs with displayed VP2-fused Fc-scFv molecule showed higher antigen-binding activity and HBV-neutralizing capacity that might be explained by a better accessibility of the Fc-engineered scFv of the VLP surface. Conclusions: Polyomavirus-derived pseudotype VLPs harbouring multiple functionally active antibody molecules with virus-neutralizing capability may represent a novel platform for developing therapeutic tools with a potential application for post-exposure or therapeutic treatment of viral infections

Quantification of large and middle proteins of hepatitis B virus surface antigen (HBsAg) as a novel tool for the identification of inactive HBV carriers

Objective Among individuals with chronic hepatitis B, those with hepatitis B e-antigen (HBeAg)-negative chronic hepatitis (CHB) can be difficult to distinguish from those with HBeAg-negative chronic HBV infection, also referred to as inactive HBV carriers (ICs), but both require different medical management. The level of HBV surface antigen (HBsAg) has been proposed as a marker to discriminate between chronic infection and hepatitis stages. HBsAg consists of large, middle and small HBs. The aim of this study was to determine whether the composition of HBsAg improved the identification of ICs among HBsAg-positive subjects with different phases of HBV infections. Design HBV large surface proteins (LHBs) and HBV middle surface proteins (MHBs) were quantified in serum samples from 183 clinically well-characterised untreated patients with acute (n=14) HBV infection, ICs (n=44), CHBs (n=46), chronic HBeAg-positive phase (n=68) and hepatitis delta coinfection (n=11) using an ELISA, with well-defined monoclonal antibodies against the preS1 domain (LHBs) and the preS2-domain (MHBs). A Western blot analysis was used to verify the quantitation of the components of HBsAg. Total HBsAg was quantified using a modified commercially available assay (HBsAg V. 6.0, Enzygnost, Siemens, Erlangen). Results The composition of HBsAg showed specific patterns across different phases of hepatitis B. Individuals in the IC phase had significantly lower proportions of LHBs and MHBs than patients in acute or chronic phases irrespective of their HBV e-antigen status (p< 0.0001) or HBsAg level. Both LHBs and MHBs ratios better predicted the IC phase than total HBsAg levels. Conclusion Quantification of MHBs, particularly LHBs represents a novel tool for the identification of the IC stage

A) Titration curve of humAb binding to HBsAg in an ELISA.

<p>Diamonds: ADRI-2F3, Squares: PK-3D1, Triangles PK-10C7. B) Western blot showing reactivity of humAb ADRI-2F3 (lanes 1 and 2), PK-10C7 (lane 3) and PK-3D1 (lane 4). Lane 5; positive control serum, lane 6; negative control. MW indicates a molecular weight marker. Note that in lanes 3, 4 and 5 a 24 kDa band is recognized, indicating binding to the HBsAg polypeptide. C) Competitive inhibition of serial dilutions (0 ng/ml—400 ng/ml) of humAb ADRI-2F3, and its corresponding recombinant recADR12F3, binding to HBsAg by 200 ng of murine mAb Hyb-824 specific for the HBsAg common “a” determinant. D) Competitive inhibition of humAb ADRI-2F3, recADRI2F3, PK-10C7, PK-3D1 by murine mAb Hyb-824. CM3B6, a HCV-NS3 specific humAb, served as negative control. Co20-F10 is an isotype control.</p

Neutralizing activity of three human monoclonal antibodies PK-3D1, PK-10C7 and ADRI-2F3 in comparison with mouse monoclonal antibody MA18/7.

<p>It is shown herein that a dilution of 1:10,000 of monoclonal antibody supernatant ADRI-2F3 completely neutralizes the activity of HBV, whereas EC50 is reached at a dilution of 1: 100,000.</p

Hepatitis B virus subgenotype F3 reactivation with vaccine escape mutations: A case report and review of the literature

Hepatitis B represents a global health threat because its chronic course and sequelae contribute to a high morbidity and mortality. Hepatitis B virus (HBV) infection can be controlled by vaccines, antiviral treatment, and by interrupting transmission. Rare vaccine escape mutants are serious because they eliminate vaccine protection. Here, we present a 74-year-old vaccinated patient with HBV reactivation 11 years after kidney transplantation. The patient was HBV-positive but HBsAg-negative prior to vaccination 6 years before transplantation. The reactivated virus was HBV genotype F3 with vaccine escape mutations G145R, P120Q, and Q129P. The patient was successfully treated with entecavir. The epidemiological reasons for this sub-genotype, which is extremely rare in Western Europe, were unclear. This case illustrates that second-generation vaccines are not always effective in a specific group of patients

Quantitation of large, middle and small hepatitis B surface proteins in HBeAg-positive patients treated with peginterferon alfa-2a.

BACKGROUND & AIMS: Hepatitis B virus (HBV) contains three viral surface proteins, large, middle and small hepatitis B surface protein (LHBs, MHBs, SHBs). Proportions of LHBs and MHBs are lower in patients with inactive versus active chronic infection. Interferon alfa may convert HBeAg-positive chronic hepatitis B (CHB) to an inactive carrier state, but prediction of sustained response is unsatisfactory. The aim of this study was to test the hypothesis that quantification of MHBs and LHBs may allow for a better prognosis of therapeutic response than total hepatitis B surface antigen (HBsAg) concentration. METHODS: HBs proteins were measured before and during peginterferon alfa-2a therapy in serum from 127 Asian patients with HBeAg-positive CHB. Sustained response was defined as hepatitis B e antigen (HBeAg) seroconversion 24 weeks post-treatment. RESULTS: Mean total HBs levels were significantly lower in responders versus nonresponders at all time points (P0.70). CONCLUSIONS: HBs proteins levels differ by HBV genotype. However, quantification of HBs proteins has no advantage over the already established HBsAg assays to predict response to peginterferon alfa-2a therapy in HBeAg-positive patients

A Human Monoclonal Antibody against Hepatitis B Surface Antigen with Potent Neutralizing Activity

<div><p>We describe the production and characterization of human monoclonal antibodies (mAb) specific for the major hepatitis B virus (HBV) S protein. The mAbs, two IgG1κ and one IgG1λ, were secreted by B-cell clones obtained from peripheral blood mononuclear cells (PBMC) of one person convalescent from acute hepatitis B and one vaccinated individual. The former recognized a denaturation-insensitive epitope within the p24 protein whereas the latter recognized a denaturation-sensitive, conformational epitope located within the HBsAg common “a” determinant. This mAb, denominated ADRI-2F3, displayed a very high protective titer of over 43,000 IU/mg mAb and showed an extremely potent neutralizing activity in the in vitro model of HBV infection using primary hepatocytes from <i>Tupaia belangeri</i> as target. Recombinant variable heavy and light domain sequences derived from mAb ADRI-2F3 were cloned into eukaryotic expression vectors and showed identical fine specificity and 1 log₁₀ higher titer than the original IgG1λ. It is envisaged that such mAb will be able to efficiently prevent HBV reinfection after liver transplantation for end-stage chronic HBV infection or infection after needle-stick exposure, providing an unlimited source of valuable protective anti-HBs antibody.</p></div

Bats carry pathogenic hepadnaviruses antigenically related to hepatitis B virus and capable of infecting human hepatocytes

The hepatitis B virus (HBV), family Hepadnaviridae, is one of most relevant human pathogens. HBV origins are enigmatic, and no zoonotic reservoirs are known. Here, we screened 3,080 specimens from 54 bat species representing 11 bat families for hepadnaviral DNA. Ten specimens (0.3%) from Panama and Gabon yielded unique hepadnaviruses in coancestral relation to HBV. Full genome sequencing allowed classification as three putative orthohep