Characterization of HDV-specific antisera with respect to the recognized epitopes

Introduction Many steps of the Hepatitis D virus (HDV) life cycle remain enigmatic and diagnostic screenings are suboptimal leading to underestimation. Highly sensitive HDV-specific antibodies are needed for research and diagnosis. This study aims to characterize epitopes recognized by HDV specific antibodies.

Methods Two rabbits were immunized with the purified S-HDAg either in its native or in a denatured form. Epitope mapping of obtained hyperimmune sera was performed using peptide arrays synthetic peptides covering the full-length S-HDAg protein.

Results Epitope mapping revealed several highly reactive B-cell epitopes mainly in the C-terminal S-HDAg-region. Antisera obtained by immunization with denatured S-HDAg were more polyclonal as reflected by more recognized epitopes. Projection of these epitopes into a 3D model of S-HDAg revealed shielding of these epitopes in the native state. For instance, epitope DENPWLGNI is localized in the dimerization domain of S HDAg and is shielded in the oligomeric state of native S-HDAg. This prevents recognition in case of immunization with the native protein. In contrast to this, epitope EDERRERRVA is localized within the more accessible RNA binding domain of S-HDAg and therefore is recognized during immunization by native S-HDAg.

Conclusion We identified highly immunogenic S-HDAg epitopes, which are accessible in the native conformation of S-HDAg and can be used for generation of highly specific S-HDAg-specific monoclonals. Furthermore, synthetic peptides bearing these epitopes can be used as potential vaccine candidates. The sera obtained in this study can be used for CLSM-based analysis of HDV life cycle and for quantitative analysis of HDAg.

Publikationsverlauf

Artikel online veröffentlicht:
23. Januar 2024