Epitope mapping and characterization of a neutralizing monoclonal antibody against human adenovirus type 3

Human adenovirus serotype 3 (HAdV-3) has occurred as a global epidemic in recent years causing serious diseases such as pneumonia in pediatric and adult patients. Development of reliable diagnostic reagents and identification of neutralizing epitopes is important for the surveillance and control of infection. In this study, a neutralizing monoclonal antibody (MAb) MAb 1B6 was generated using the HAdV-3 virion. MAb 1B6 specially recognized the HAdV-3 virus particles and the HAdV-3 hexon protein, but not the virus particles or the hexon protein of HAdV-7 and HAdV-4 by western-blot analysis and indirect enzyme-linked immunosorbent assay (ELISA). Analysis using a series of peptides from the hexon protein and chimeric adenovirus (Ad) particles of epitope mutants revealed that MAb 1B6 bound to the exposed region (amino acid positions 414-424 of hexon) in hypervariable region 7 (HVR7). ELISA demonstrated that MAb 1B6 could recognize the corresponding regions of other HAdV-3 genotypes that have some residues substituted. The identification of the neutralizing epitope and the generation of MAb 1B6 may be useful for clinical serotype-specific diagnosis, subunit vaccine construction for HAdV-3 infection, and virion structural analysis.