Identification of a conformational neutralizing epitope on the VP1 protein of type A foot-and-mouth disease virus

Ren

et al. 2021

Vaccines

Canine adenovirus (CAdV) has a high prevalence in canine populations. High affinity neutralizing antibodies against conserved epitopes can provide protective immunity against CAdV and protect against future outbreaks. In this study, we identified two CAdV-2-specific neutralizing monoclonal antibodies (mAbs), 2C1 and 7D7, which recognized two linear-dependent epitopes. MAb 2C1 potently neutralized CAdV-2 with a 50% neutralization titer (NT50) of 4096, and mAb 7D7 partially neutralized CAdV-2 with a 50% NT50 of 64. Immunoprecipitation, Western blot and protein spectral analysis indicated that both neutralizing mAbs recognized the hexon protein (Hex) of CAdV-2. Through a 12-mer random peptide phage display and synthetic peptides analysis, we finely mapped the neutralizing epitopes to two 10-amino acid (aa) peptides within the CAdV Hex: 634RIKQRETPAL643 located on the surface region; and 736PESYKDRMYS745 located in the inner region of the expected 3D structure of trimeric Hex. Importantly, the two epitopes are highly conserved among all CAdV isolates by sequence alignment analysis. Thus, these results provide insights into the interaction between virus and mAbs at the aa level and may have potential applications in the development of novel therapeutic or epitope-based vaccines, antibody therapeutics and a diagnostic method suitable for the rapid detection of all CAdVs.

Section: Discussionmentioning

confidence: 99%

“…The experiment was repeated 3 times. The Kärber method was used to calculate the 50% neutralizing titer (NT50) [17,18].…”

Section: Micro-neutralization Assaymentioning

confidence: 99%

Identification of Two Novel Linear Neutralizing Epitopes within the Hexon Protein of Canine Adenovirus Using Monoclonal Antibodies

Ren

et al. 2021

Vaccines

“…Epitopes are also known as antigenic determinants, which are composed of specific amino acid or chemical groups on the antigen molecule that determine the specificity of the antigen. Epitope identification includes epitope peptide scanning, protein cleavage, and phage display technology [29,30]. In this study, the eukaryotic expression vector pEGFP-C3 was used to express truncated VP3 protein to identify epitopes.…”

Section: Discussionmentioning

confidence: 99%

Identification of a B-Cell Epitope in the VP3 Protein of Senecavirus A

Chen

et al. 2021

Viruses

Senecavirus A (SVA) is a member of the genus Senecavirus of the family Picornaviridae. SVA-associated vesicular disease (SAVD) outbreaks have been extensively reported since 2014–2015. Characteristic symptoms include vesicular lesions on the snout and feet as well as lameness in adult pigs and even death in piglets. The capsid protein VP3, a structural protein of SVA, is involved in viral replication and genome packaging. Here, we developed and characterized a mouse monoclonal antibody (mAb) 3E9 against VP3. A motif 192GWFSLHKLTK201 was identified as the linear B-cell epitope recognized by mAb 3E9 by using a panel of GFP-tagged epitope polypeptides. Sequence alignments show that 192GWFSLHKLTK201 was highly conserved in all SVA strains. Subsequently, alanine (A)-scanning mutagenesis indicated that W193, F194, L196, and H197 were the critical residues recognized by mAb 3E9. Further investigation with indirect immunofluorescence assay indicated that the VP3 protein was present in the cytoplasm during SVA replication. In addition, the mAb 3E9 specifically immunoprecipitated the VP3 protein from SVA-infected cells. Taken together, our results indicate that mAb 3E9 could be a powerful tool to work on the function of the VP3 protein during virus infection.

“…These broadly neutralizing antibodies can be applied to identify conserved epitopes of FMDV and to guide the rational design of universal FMDV vaccines. Work is under way to identify conserved epitopes by selecting MAb neutralization-resistant mutants (26) or screening a phage-displayed random 12-peptide library (27,28). Neutralizing monoclonal antibodies can also be used for the development of detection methods.…”

Section: Discussionmentioning

confidence: 99%

Implication of Broadly Neutralizing Bovine Monoclonal Antibodies in the Development of an Enzyme-Linked Immunosorbent Assay for Detecting Neutralizing Antibodies against Foot-and-Mouth Disease Virus Serotype O

Cao

et al. 2019

J Clin Microbiol

Vaccination with inactivated vaccines is still the main measure to control foot-and-mouth disease (FMD) in areas where the disease is endemic, and the level of neutralizing antibody in vaccinated animals is directly related to their protection against virus challenge. Currently, neutralizing antibody is mainly detected using the virus neutralization test (VNT) based on cell culture, which is laborious and time-consuming and requires restrictive biocontainment facilities. In this study, two broadly neutralizing antibodies (bnAbs), E46 and F128, were successfully produced using techniques for the isolation of single B cells from peripheral blood mononuclear cells (PBMCs) from bovines sequentially immunized with three topotypes of foot-and-mouth disease virus (FMDV) serotype O. Based on these bnAbs, a blocking enzyme-linked immunosorbent assay (ELISA) for detecting neutralizing antibodies (NA-ELISA) against FMDV serotype O was developed. The specificity and sensitivity of the test were estimated to be 99.21% and 100%, respectively. A significant correlation (P < 0.01) was observed between the NA-ELISA titers and the VNT titers for all sera from vaccinated animals and for all tested strains, suggesting that the NA-ELISA could detect neutralizing antibodies against FMDV serotype O strains of wide antigenic and molecular diversity and could be used for the evaluation of protective immunity.