neutralizing epitope
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Viruses ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 125
Author(s):  
Techit Thavorasak ◽  
Monrat Chulanetra ◽  
Kittirat Glab-ampai ◽  
Karsidete Teeranitayatarn ◽  
Thaweesak Songserm ◽  
...  

Porcine epidemic diarrhea virus (PEDV) causes devastating enteric disease that inflicts huge economic damage on the swine industry worldwide. A safe and highly effective PEDV vaccine that contains only the virus-neutralizing epitopes (not enhancing epitope), as well as a ready-to-use PEDV neutralizing antibody for the passive immunization of PEDV vulnerable piglets (during the first week of life) are needed, particularly for PEDV-endemic farms. In this study, we generated monoclonal antibodies (mAbs) to the recombinant S1 domain of PEDV spike (S) protein and tested their PEDV neutralizing activity by CPE-reduction assay. The mAb secreted by one hybrodoma clone (A3), that also bound to the native S1 counterpart from PEDV-infected cells (tested by combined co-immunoprecipitation and Western blotting), neutralized PEDV infectivity. Epitope of the neutralizing mAb (mAbA3) locates in the S1A subdomain of the spike protein, as identified by phage mimotope search and multiple sequence alignment, and peptide binding-ELISA. The newly identified epitope is shared by PEDV G1 and G2 strains and other alphacoronaviruses. In summary, mAbA3 may be useful as a ready-to-use antibody for passive immunization of PEDV-susceptible piglets, while the novel neutralizing epitope, together with other, previously known protective epitopes, have potential as an immunogenic cocktail for a safe, next-generation PEDV vaccine.


2021 ◽  
Author(s):  
Jiale Shi ◽  
Yuejun Shi ◽  
Ruixue Xiu ◽  
Gang Wang ◽  
Rui Liang ◽  
...  

The receptor binding domain (RBD) of the coronavirus spike protein (S) has been verified to be the main target for potent neutralizing antibodies (nAbs) in most coronaviruses, and the N-terminal domain (NTD) of some betacoronaviruses has also been indicated to induce nAbs. For alphacoronavirus HCoV-229E, its RBD has been shown to have neutralizing epitopes, and these epitopes could change over time. However, whether neutralizing epitopes exist on the NTD and whether these epitopes change like those of the RBD are still unknown. Here, we verified that neutralizing epitopes exist on the NTD of HCoV-229E. Furthermore, we characterized an NTD targeting nAb 5H10, which could neutralize both pseudotyped and authentic HCoV-229E VR740 in vitro. Epitope mapping indicated that 5H10 targeted motif E1 (147-167 aa) and identified F159 as critical for 5H10 binding. More importantly, our results revealed that motif E1 was highly conserved among clinical isolates except for F159. Further data proved that mutations at position 159 gradually appeared over time and could completely abolish the neutralizing ability of 5H10, supporting the notion that position 159 may be under selective pressure during the human epidemic. In addition, we also found that contemporary clinical serum has a stronger binding capacity for the NTD of contemporary strains than historic strains, proving that the epitope on the NTD could change over time. In summary, these findings define a novel neutralizing epitope on the NTD of HCoV-229E S and provide a theoretical basis for the design of vaccines against HCoV-229E or related coronaviruses. Importance Characterization of the neutralizing epitope of the spike (S) protein, the major invasion protein of coronaviruses, can help us better understand the evolutionary characteristics of these viruses and promote vaccine development. To date, the neutralizing epitope distribution of alphacoronaviruses is not well known. Here, we identified a neutralizing antibody that targeted the N-terminal domain (NTD) of the alphacoronavirus HCoV-229E S protein. Epitope mapping revealed a novel epitope that was not previously discovered in HCoV-229E. Further studies identified an important residue, F159. Mutations that gradually appeared over time at this site abolished the neutralizing ability of 5H10, indicating that selective pressure occurred at this position in the spread of HCoV-229E. Furthermore, we found that the epitopes within the NTD also changed over time. Taken together, our findings defined a novel neutralizing epitope and highlighted the role of the NTD in the future prevention and control of HCoV-229E or related coronaviruses.


2021 ◽  
Author(s):  
Wei Wen ◽  
Xinghua Chen ◽  
Qiang Lv ◽  
Huanchun Chen ◽  
Ping Qian ◽  
...  

Abstract Background Seneca Valley virus (SVV) is a picornavirus that causes vesicular disease in swine. Clinical characteristics of the disease is similar to common viral diseases such as foot-and-mouth disease virus, porcine vesicular disease virus, and vesicular stomatitis virus, which can cause vesicles in the nose or hoof of pigs. Therefore, developing tools for detecting SVV infection is critical and urgent. Methods The neutralizing antibodies were produced to detect the neutralizing epitope. Results Five SVV neutralizing monoclonal antibodies (mAb), named 2C8, 3E4, 4C3, 6D7, and 7C11, were generated by immunizing mouses with ultra-purified SVV-LNSY01-2017. All five monoclonal antibodies exhibited high neutralizing titers to SVV. The epitopes targeted by these mAbs were further identified by peptide scanning using GST fusion peptides. The 153QELNEE158 peptide is defined as the smallest linear neutralizing epitope. The antibodies showed no reactivity to VP2 single mutants E157A. Furthermore, the antibodies showed no neutralizing activity with the recombinant virus (SVV-E157A). Conclusion The five monoclonal antibodies and identified epitopes may contribute to further research on the structure and function of VP2 and the development of diagnostic methods for detecting different SVV strains. Additionally, the epitope recognized by monoclonal antibodies against VP2 protein may provide insights for novel SVV vaccines and oncolytic viruses development.


Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1084
Author(s):  
Fengsai Li ◽  
Xiaona Wang ◽  
Xiaolong Fan ◽  
Ling Sui ◽  
Hailin Zhang ◽  
...  

Porcine epidemic diarrhea (PED), which is caused by the porcine epidemic diarrhea virus (PEDV), has occurred worldwide and poses a serious threat to the pig industry. Intestine is the main function site of PEDV; therefore, it is important to develop an oral mucosal immunity vaccine against this virus infection. Most traditional plasmid delivery vectors use antibiotic genes as a selective marker, easily leading to antibiotic accumulation and gene contamination. In this study, to explore whether the alanine racemase gene (Alr) could be used as a screening marker and develop an efficient oral vaccine against PEDV infection, a recombinant strain was constructed using Lactobacillus casei with Alr deletion (L. casei ΔAlr W56) to deliver the Alr gene and a core-neutralizing epitope (COE) antigen. This recombinant bacterium efficiently induced secretory immunoglobulin A (SIgA)-based mucosal and immunoglobulin G (IgG)-based humoral immune responses via oral vaccination in mice. Compared to the other strains, the recombinant bacteria were able to grow without the addition of D-alanine, revealing that Alr in the plasmid could function normally in defective bacteria. This oral mucosal vaccine would provide a useful strategy to substitute the application of antibiotics in the future and induce efficient immune responses against PEDV infection.


2021 ◽  
Author(s):  
Clara Gilda Altomare ◽  
Daniel Cole Adelsberg ◽  
Juan Manuel Carreno ◽  
Iden Avery Sapse ◽  
Fatima Amanat ◽  
...  

Structural characterization of infection- and vaccination-elicited antibodies in complex with antigen provides insight into the evolutionary arms race between the host and the pathogen and informs rational vaccine immunogen design. We isolated a germline-like monoclonal antibody (mAb) from plasmablasts activated upon mRNA vaccination against SARS-CoV-2 and determined its structure in complex with the spike glycoprotein by cryo-EM. We show that the mAb engages a previously uncharacterized neutralizing epitope on the spike N-terminal domain (NTD). The high-resolution structure reveals details of the intermolecular interactions and shows that the mAb inserts its HCDR3 loop into a hydrophobic NTD cavity previously shown to bind a heme metabolite, biliverdin. We demonstrate direct competition with biliverdin and that - because of the conserved nature of the epitope - the mAb maintains binding to viral variants B.1.1.7 and B.1.351. Our study illustrates the feasibility of targeting the NTD to achieve broad neutralization against SARS-CoV-2 variants.


2021 ◽  
Vol 135 ◽  
pp. 45-52
Author(s):  
Jinning Wei ◽  
Xin Cheng ◽  
Yi Zhang ◽  
Chen Gao ◽  
Ying Wang ◽  
...  

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 683
Author(s):  
Ki-Jong Kang ◽  
Dong-Hwan Kim ◽  
Eui-Ju Hong ◽  
Hyun-Jin Shin

In this study, we evaluated 62 sow sera samples from PED-vaccinated sows to compare the serum neutralizing test (SNT) and enzyme-linked immunosorbent assay (ELISA). We performed protein ELISA (pELISA) using fragments of spike proteins S1, S2, S3 and entire nucleocapsid proteins, and found a correlation between the SNT and ELISA in PEDV-vaccinated sera. Sera with higher neutralizing activity showed higher titers of IgG. In the antibody profiling, the neutralizing activities are correlated with the levels of the spike antibody, especially the S3 region. We confirmed that the carboxy-terminal region, including the endodomain of the S protein, induced stronger neutralizing activity than the ectodomain. This region of the S protein could be useful for evaluating PED vaccine efficacy, and it is a strong neutralizing epitope of PEDV. The S3 protein could be useful for evaluating PED vaccine efficacy, and it is a strong neutralizing epitope of PEDV.


2021 ◽  
pp. 198409
Author(s):  
Zenglei Hu ◽  
Jiangyan Zhao ◽  
Lei Shi ◽  
Jiao Hu ◽  
Shunlin Hu ◽  
...  

Author(s):  
Yimin Huang ◽  
Annalee W. Nguyen ◽  
Ching-Lin Hsieh ◽  
Rui Silva ◽  
Oladimeji S. Olaluwoye ◽  
...  

ABSTRACTThree pathogenic human coronaviruses have emerged, with SARS-CoV-2 causing a global pandemic. While therapeutic antibodies targeting the SARS-2 spike currently focus on the poorly conserved receptor-binding domain, targeting essential neutralizing epitopes on the more conserved S2 domain may provide broader protection. We report three antibodies, binding epitopes conserved on the pre-fusion MERS, SARS-1 and SARS-2 spike S2 domains. Antibody 3A3 binds a conformational epitope with ~2.5 nM affinity and neutralizes in in vitro SARS-2 cell fusion and pseudovirus assays. Hydrogen-deuterium exchange mass spectrometry identified residues 980-1006 in the flexible hinge region at the S2 apex as the 3A3 epitope, consistent with binding to natural and engineered spike variants. This location at the spike trimer interface suggests 3A3 prevents the S2 conformational rearrangements required for virus-host cell fusion. This work defines a highly conserved vulnerable site on the SARS-2 S2 domain and may help guide the design of pan-protective spike immunogens.TEASERA conserved, neutralizing epitope in the S2 domain of coronavirus spike was identified as a target for pan-coronavirus therapy and vaccination.


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