Identification of a potential neutralizing linear epitope of hemagglutinin-neuraminidase in Newcastle disease virus

Zhongyuan Jin,Yongshan Li,Youkun Bi,Zengqi Yang,Sujing Mou,Haijin Liu,Wenbin Wang,Hongjun Chen,Sa Xiao,Na Huo,Qiaolin Wei

doi:10.1186/s12985-020-01483-y

Abstract

BackgroundThe hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) is a major antigen that can induce protective antibodies in poultry. However, its antigenic epitopes have not been fully elucidated. Therefore, defining the linear epitopes of HN, especially neutralizing epitopes, will be useful for revealing its antigenic characterization.MethodsIn this study, we analyzed B-cell immunodominant epitopes (IDEs) of the HN protein from the vaccine strain LaSota using pepscan technology with LaSota-specific chicken hyperimmune antisera. We constructed IDEs-RFP plasmids and prepared anti-IDEs peptide mouse sera to identify IDEs through immunological tests. At last, the different diluted anti-IDE antisera were used in BHK-21 cells to perform the neutralization test.ResultsFive IDEs of the HN were screened and further verified by indirect immunofluorescence assays, dot blots and Western blots with NDV- and IDEs-specific antisera. All five IDEs showed good immunogenicity. IDE5 (328–342 aa) could recognize only class II NDV but did not react with the class I strain. Most of the IDEs are highly conserved among the different strains. A neutralization test in vitro showed that the peptide-specific mouse antisera of IDE4 (242–256 aa) and HN341-355, a reported neutralizing linear epitope, could partially neutralize avirulent LaSota as well as virulent strains at similar levels, suggesting that IDE4 might be a potential neutralizing linear epitope.ConclusionThe HN protein is a major protective antigen of NDV that can induce neutralizing antibodies in animals. We identified five IDEs of the HN using a pepscan approach with NDV-specific chicken hyperimmune antisera. The five IDEs could elicit specific antibodies in mice. IDE4 (242–256 aa) was identified as a novel potential neutralizing linear epitope. These results will help elucidate the antigenic epitopes of the HN and facilitate the development of NDV vaccines.

Highlights

The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) is a major antigen that can induce protective antibodies in poultry
Newcastle disease (ND) is a highly contagious disease of birds that causes major economic losses in the poultry industry worldwide [1, 2]. It is caused by Newcastle disease virus (NDV), known as avian paramyxovirus serotype 1 (APMV-1) or orthoavulavirus-1, which is currently classified into the genus Orthoavulavirus
We examined whether the HN protein can be recognized by NDV-specific chicken antisera

Summary

Introduction

The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) is a major antigen that can induce protective antibodies in poultry. HN, a surface glycoprotein of NDV, plays multiple roles in viral tropism and virulence [7] This protein consists of a cytoplasmic domain, transmembrane region, stalk region and globular head [8] and is responsible for binding to sialic acid-containing cell surface receptors and possesses neuraminidase (NA) activity to prevent viral self-aggregation. HN, as a major protective antigen, can induce virus-neutralizing antibodies during NDV infection [12, 13]. Its corresponding mAb 14 could neutralize NDV [16] This epitope in the infectious bursal disease virus-vectored vaccine could induce protective antibodies in chickens against NDV [17]. Defining the linear epitopes of HN, especially neutralizing epitopes, will be useful for revealing its antigenic characterization

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Results

Discussion

Conclusion