Hepatitis E virus (HEV) is responsible for over 50% of acute viral hepatitis cases worldwide. The inventors have now identified the precise sequence of infectious particle-associated ORF2 capsid protein. Strikingly, their analyses revealed that in infected patients, HEV produces three forms of the ORF2 capsid protein: ORF2i, ORF2g and ORF2c. The ORF2i protein is associated with infectious particles whereas ORF2g and ORF2c proteins are massively produced glycoproteins that are not associated with infectious particles and are the major antigens present in HEV-infected patient sera. Accordingly, the ORF2i and ORF2g proteins are thus the subject matter of the present invention as well as antibodies specific for the proteins and diagnostic assays (e.g. ELISA) for the diagnosis of Hepatitis E virus infection.

The present invention relates to Coronavirus 2019-nCOV spike protein, polynucleotides encoding said spike protein, antibodies and vaccines for treatment or prevention of 2019-nCOV infection.

Modified capsid proteins containing at least a portion of hepatitis E virus (HEV) open reading frame 2 (ORF2) having one or more cysteine residues in a surface variable loop or the C-terminus of HEV ORF2, or a portion thereof, are provided. The modified capsid proteins can be used to form hepatitis E virus (HEV) virus like particles (VLPs) having cysteine functional groups exposed on the outer-surface. The exposed cysteine functional groups can be modified via their thiol reactive group. For example, a bioactive agent, such as a cell-targeting ligand, can be conjugated to the one or more cysteines for targeted delivery of chemically activated nanocapsids.

Polypeptides of the p-ORF2 protein of the hepatitis E virus, including at least the amino acid sequence 394-660, numbered in relation to a p-ORF2 protein of 660 amino acids, in which the three cysteines at positions 627, 630 and 638 have been mutated or, for a p-ORF2 protein of different length, at least the amino acid sequence corresponding to amino acids 394-660 of the p-ORF2 protein of 660 amino acids, in which the three cysteines located at the three positions corresponding to positions 627, 630 and 638 of the p-ORF2 protein of 660 amino acids have been mutated. Also, methods for determining the presence of the humoral response or the titer of antibodies directed against the p-ORF2 protein using these polypeptides, and also the use thereof in the context of infection with the hepatitis E virus.

The present disclosure provides affinity tagged heterodimeric polypeptides comprising a hepatitis C virus (HCV) E1 polypeptide and an HCV E2 polypeptide, where one or both of the E1 and E2 polypeptides comprises an affinity tag. The present disclosure provides a method of producing an affinity tagged E1/E2 heterodimer of the present disclosure. The present disclosure provides methods of producing untagged HCV E1/E2 heterodimers. The present disclosure provides HCV E1/E2 heterodimers, compositions comprising same, and methods of inducing an immune response to HCV.

Modified capsid proteins containing at least a portion of hepatitis E virus (HEV) open reading frame 2 (ORF2) having one or more cysteine residues in a surface variable loop or the C-terminus of HEV ORF2, or a portion thereof, are provided. The modified capsid proteins can be used to form hepatitis E virus (HEV) virus like particles (VLPs) having cysteine functional groups exposed on the outer-surface. The exposed cysteine functional groups can be modified via their thiol reactive group. For example, a bioactive agent, such as a cell-targeting ligand, can be conjugated to the one or more cysteines for targeted delivery of chemically activated nanocapsids.

The present disclosure provides affinity tagged heterodimeric polypeptides comprising a hepatitis C virus (HCV) E1 polypeptide and an HCV E2 polypeptide, where one or both of the E1 and E2 polypeptides comprises an affinity tag. The present disclosure provides a method of producing an affinity tagged E1/E2 heterodimer of the present disclosure. The present disclosure provides methods of producing untagged HCV E1/E2 heterodimers. The present disclosure provides HCV E1/E2 heterodimers, compositions comprising same, and methods of inducing an immune response to HCV.

Provided in the present invention are a diphtheria toxin non-toxic mutant CRM197 or a fragment thereof as an adjuvant in a fusion protein and the use thereof to enhance the immunogenicity of a target protein fused therewith, for example, an HEV capsid protein, or an influenza virus M2 protein or an immunogenic fragment thereof. Also provided is a method for enhancing the immunogenicity of a target protein, comprising the fusion expression of the CRM197 or the fragment thereof with the target protein to form a fusion protein. Further provided is a fusion protein comprising the CRM197 or the fragment thereof and a target protein, the CRM197 or the fragment thereof enhancing the immunogenicity of the target protein. The present invention also provides an isolated nucleic acid encoding the fusion protein, a construct and a vector comprising said nucleic acid, and a host cell comprising the nucleic acid.

Provided in the present invention are a diphtheria toxin non-toxic mutant CRM197 or a fragment thereof as an adjuvant in a fusion protein and the use thereof to enhance the immunogenicity of a target protein fused therewith, for example, an HEV capsid protein, or an influenza virus M2 protein or an immunogenic fragment thereof. Also provided is a method for enhancing the immunogenicity of a target protein, comprising the fusion expression of the CRM197 or the fragment thereof with the target protein to form a fusion protein. Further provided is a fusion protein comprising the CRM197 or the fragment thereof and a target protein, the CRM197 or the fragment thereof enhancing the immunogenicity of the target protein. The present invention also provides an isolated nucleic acid encoding the fusion protein, a construct and a vector comprising said nucleic acid, and a host cell comprising the nucleic acid.

A Hepatitis E virus (HEV)-based virus like nanoparticle (HEVNP) made with a modified capsid protein containing at least a portion of open reading frame 2 (ORF2) protein conjugated with gold nanocluster is provided. Also provided are methods of targeted delivery of a nucleic acid using the HEVNP.