Cross-reactive neutralizing antibody epitopes against Enterovirus 71 identified by an in silico approach

Currently, infections of hand, foot and mouth disease HFMD) due to Human Enterovirus 71 (EV71) cannot be prevented or treated, as there are no suitable vaccines or antiviral drugs. This study aimed to identify potential vaccine candidates for EV71 using in silico analysis of its viral capsid proteins. A combined in silico approach utilizing computational hidden Markov model (HMM), propensity scale algorithm, and artificial learning, identified three 15-mer structurally conserved B-cell epitope candidates lying within the EV71 capsid proteins. Peptide vaccine candidates incorporating a target B-cell epitope and a promiscuous T-cell epitope from the related polio virus were synthesized using solid-phase Fmoc chemistry. Inbred BALB/C mice which were inoculated with two 10μg doses of the synthetic peptide, generated anti-peptide antibodies. Purified IgG isolated from pooled sera of the inoculated mice neutralized EV71 infections in vitro. Furthermore, these neutralizing antibodies were cross-reactive against other members of the Picornaviridae family, demonstrating greater than 50% virus neutralization. This indicates that the current approach is promising for the development of synthetic peptide-based vaccine candidates against Picornaviridae. Development of effective vaccines is of paramount importance in managing the disease in the Asia Pacific regions where this virus is endemic and has significant social, economic and public health ramifications

Exploiting information inherent in binding sites of virus-specific antibodies: design of an HCV vaccine candidate cross-reactive with multiple genotypes

C1 - Journal Articles RefereedBACKGROUND/AIMS: The role of antibody in hepatitis C virus (HCV) infection remains unclear although many reports attest to its role in viral clearance. Here we describe epitopes that are recognized by antibody present in the serum of infected patients and show that such epitopes can induce neutralizing antibodies. METHODS: Human serum containing hyperimmune anti-HCV IgG was used to extract epitopes from a library of synthetic peptides that encompassed the sequences of the E1 and E2 proteins of HCV genotype 1a H77. Peptides that were bound by IgG were identified by mass spectrometry. Assembly of these epitopes with a helper T cell determinant was then carried out in order to construct candidate epitope-based vaccines. RESULTS: Three distinct antigenic sites were defined in the E1E2 glycoproteins by epitopes identified by antibody present in infected individuals. Four of the peptide epitopes identified are conserved in at least three HCV genotypes and are bound by antibody present in the sera of chronically infected and convalescent individuals. Synthetic vaccines based on these epitopes elicited antibodies that are capable of (i) capturing HCV virions from the serum of viraemic patients and (ii) inhibiting HCV pseudovirus particle entry into Huh7 cells. CONCLUSIONS: This approach exploits the information inherent in the binding sites of virus-specific antibodies and represents a novel method for the design of synthetic epitope-based vaccines

Cross-reactive epitopes identified in hepatitis C virus envelope proteins induce antibodies that capture virions from infected patients' sera and neutralize HCV/HIV pseudotypes

Abstract not available

Characterisation of a hepatitis C virus-like particle vaccine produced in a human hepatocyte-derived cell line

An effective immune response against HCV requires the early development of multi-specific class 1 CD8+ and class II CD4+ T cell together with broad neutralizing antibody (NAb) responses. We have produced mammalian cell-derived HCV VLPs incorporating core, E1 and E2 of HCV genotype 1a to produce such immune responses. Here we decribe the biochemical and morphological characterisation of the HCV VLPs and study HCV core specific T cell responses to the particles. The E1 and E2 glycoproteins in HCV VLPs formed non-covalent heterodimers and together with core protein assembled into VLPs with a buoyant density of 1.22 to 1.28 g/cm3. The HCV VLPs could be immunoprecipited with anti-ApoE and anti-ApoC. On electron microscopy the VLPs had a heterogeneous morphology and ranged in size from 40 to 80nm. The HCV VLPs demonstrated dose-dependent binding to murine-derived dendritic cells and the entry of HCV VLPs into Huh7 cells was blocked by anti-CD81 antibody. Vaccination of BALB/c mice with HCV VLPs purified from iodixanol gradients resulted in the production of neutralising antibody responses while vaccination of humanized MHC class I transgenic mice resulted in the prodution of HCV core specific CD8+ T cell responses. Furthermore, IgG purified from the sera of patients chronically infected with HCV genotypes 1a and 3a blocked the binding and entry of the HCV VLPs into Huh7 cells. These results show that our mammalian cell-derived-HCV VLPs induce humoral and HCV specific CD8+ T cell responses and will have important implications for the development of a preventative vaccine for HCV