Dataset Information

Fine mapping of the antigenic epitopes of the Gc protein of Guertu virus

ABSTRACT: Guertu virus (GTV), a newly discovered member of the genus Banyangvirus in the family Phenuiviridae, poses a potential health threat to humans and animals. The viral glycoprotein (GP) binds to host cell receptors to induce a neutralizing immune response in the host. Therefore, identification of the B-cell epitopes (BCEs) in the immunodominant region of the GTV Gc protein is important for the elucidation of the virus–host cell interactions and the development of GTV epitope assays and vaccines. In this study, an improved overlapping biosynthetic peptide method and rabbit anti-GTV Gc polyclonal antibodies were used for fine mapping of the minimal motifs of linear BCEs of the GTV Gc protein. Thirteen BCE motifs were identified from eleven positive 16mer-peptides, namely EGc1 (19KVCATTGRA27), EGc2 (58KKINLKCKK66), EGc3 (68SSYYVPDA75), EGc4 (75ARSRCTSVRR84), EGc5 (79CTSVRRCRWA88), EGc6 (90DCQSGCPS97), EGc7 (96PSHFTSNS103), EGc8 (115AGLGFSG121), EGc9 (148ENPHGVI154), EGc10 (179KVFHPMS185), EGc11 (230QAGMGVVG237), EGc12 (303RSHDSQGKIS312), and EGc13 (430DIPRFV435). Of these, 7 could be recognized by GTV IgG-positive sheep sera. Three-dimensional structural analysis revealed that all 13 BCEs were present on the surface of the Gc protein. Sequence alignment of the 13 BCEs against homologous proteins from 10 closely related strains of severe fever with thrombocytopenia syndrome virus from different geographical regions revealed that the amino acid sequences of EGc4, EGc5, EGc8, EGc11, and EGc12 were highly conserved, with 100% similarity. The remaining 8 epitopes (EGc1, EGc2, EGc3, EGc6, EGc7, EGc9, EGc10, and EGc13) showed high sequence similarity in the range of 71.43%–87.50%. These 13 BCEs of the GTV Gc protein provide a molecular foundation for future studies of the immunological properties of GTV glycoproteins and the development of GTV multi-epitope assays and vaccines.

SUBMITTER: Yusufu M

PROVIDER: S-EPMC9321374 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:UnlabelledHuman bocaviruses (HBoV1 to -4) are emerging pathogens associated with pneumonia and/or diarrhea in young children. Currently, there is no treatment or vaccination, so there is a need to study these pathogens to understand their disease mechanisms on a molecular and structural level for the development of control strategies. Here, we report the structures of six HBoV monoclonal antibody (MAb) fragment complexes, HBoV1-15C6, HBoV2-15C6, HBoV4-15C6, HBoV1-4C2, HBoV1-9G12, and HBoV1-12C1, determined by cryo-electron microscopy and three-dimensional image reconstruction to 18.0- to 8.5-Å resolution. Of these, the 15C6 MAb cross-reacted with HBoV1, HBoV2, and HBoV4, while the 4C2, 12C1, and 9G12 MAbs recognized only HBoV1. Pseudoatomic modeling mapped the 15C6 footprint to the capsid surface DE and HI loops, at the 5-fold axis and the depression surrounding it, respectively, which are conserved motifs in Parvoviridae The footprints for 4C2, 12C1, and 9G12 span the surface loops that assemble portions of the 2-/5-fold wall (a raised surface feature between the 2-fold and 5-fold axes of symmetry) and the shoulder of the 3-fold protrusions. The MAb footprints, cross reactive and strain specific, coincide with regions with high and low sequence/structural identities, respectively, on the capsid surfaces of the HBoVs and identify potential regions for the development of peptide vaccines for these viruses.ImportanceHuman bocaviruses (HBoVs) may cause severe respiratory and gastrointestinal infections in young children. The nonenveloped parvovirus capsid carries determinants of host and tissue tropism, pathogenicity, genome packaging, assembly, and antigenicity important for virus infection. This information is currently unavailable for the HBoVs and other bocaparvoviruses. This study identifies three strain-specific antigenic epitopes on the HBoV1 capsid and a cross-reactive epitope on the HBoV1, HBoV2, and HBoV4 capsids using structures of capsid-antibody complexes determined using cryo-electron microscopy and image reconstruction. This is the first study to report the highly conserved parvovirus DE loop at the 5-fold axis as a determinant of antigenicity. Additionally, knowledge of the strain-specific and conserved antigenic epitopes of the bocaviruses can be instrumental in characterization of the virus life cycle, development of peptide vaccines, and generation of gene delivery vectors for cystic fibrosis given the strict tropism of HBoV1 for human airway epithelial cells.

Project description:Adeno-associated viruses (AAV) serve as vectors for therapeutic gene delivery. AAV9 vectors have been FDA approved, as Zolgensma, for the treatment of spinal muscular atrophy and are being evaluated in clinical trials for the treatment of neurotropic and musculotropic diseases. A major hurdle for AAV-mediated gene delivery is the presence of preexisting neutralizing antibodies in 40 to 80% of the general population. These preexisting antibodies can reduce therapeutic efficacy through viral neutralization and the size of the patient cohort eligible for treatment. In this study, cryo-electron microscopy and image reconstruction were used to define the epitopes of five anti-AAV9 monoclonal antibodies (MAbs), ADK9, HL2368, HL2370, HL2372, and HL2374, on the capsid surface. Three of these, ADK9, HL2370, and HL2374, bound to or near the icosahedral 3-fold axes, HL2368 bound to the 2/5-fold wall, and HL2372 bound to the region surrounding the 5-fold axes. Pseudoatomic modeling enabled the mapping and identification of antibody contact amino acids on the capsid, including S454 and P659. These epitopes overlap previously defined parvovirus antigenic sites. Capsid amino acids critical for the interactions were confirmed by mutagenesis, followed by biochemical assays testing recombinant AAV9 (rAAV9) variants capable of escaping recognition and neutralization by the parental MAbs. These variants retained parental tropism and had similar or improved transduction efficiency compared to AAV9. These engineered rAAV9 variants could expand the patient cohort eligible for AAV9-mediated gene delivery by avoiding preexisting circulating neutralizing antibodies. IMPORTANCE The use of recombinant adeno-associated viruses (rAAVs) as delivery vectors for therapeutic genes is becoming increasingly popular, especially following the FDA approval of Luxturna and Zolgensma, based on serotypes AAV2 and AAV9, respectively. However, high-titer anti-AAV neutralizing antibodies in the general population exempt patients from treatment. The goal of this study is to circumvent this issue by creating AAV variant vectors not recognized by preexisting neutralizing antibodies. The mapping of the antigenic epitopes of five different monoclonal antibodies (MAbs) on AAV9, to recapitulate a polyclonal response, enabled the rational design of escape variants with minimal disruption to cell tropism and gene expression. This study, which included four newly developed and now commercially available MAbs, provides a platform for the engineering of rAAV9 vectors that can be used to deliver genes to patients with preexisting AAV antibodies.

Dataset Information

Fine mapping of the antigenic epitopes of the Gc protein of Guertu virus

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets