Different Origins of Newcastle Disease Virus Hemagglutinin-Neuraminidase Protein Modulate the Replication Efficiency and Pathogenicity of the Virus.

Ji-Hui Jin,Xiao-Hui Yu,Yan-Ling Yang,Ying-Chao Ren,Guo-Zhong Zhang,Zi-Rong He,Hui-Ming Yang,Tong Liu,Jin-Long Cheng,Yang Song

doi:10.3389/fmicb.2017.01607

Abstract

To investigate the exact effects of different origins of Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) protein to the biological characteristics of the virus, we systematically studied the correlation between the HN protein and NDV virulence by exchanging the HN of velogenic or lentogenic NDV strains with the HN from other strains of different virulence. The results revealed that the rSG10 or rLaSota derivatives bearing the HN gene of other viruses exhibited decreased or increased hemadsorption (HAd), neuraminidase and fusion promotion activities. In vitro and in vivo tests further showed that changes in replication level, tissue tropism and virulence of the chimeric viruses were also consistent with these biological activities. These findings demonstrated that the balance among three biological activities caused variation in replication and pathogenicity of the virus, which was closely related to the origin of the HN protein. Our study highlights the importance of the HN glycoprotein in modulating the virulence of NDV and contributes to a more complete understanding of the virulence of NDV.

Highlights

Newcastle disease (ND) is a constant threat to the poultry industry worldwide and has caused severe economic losses
To investigate the impact of the different origins of HN proteins in Newcastle disease virus (NDV) virulence, the complete HN open reading frame (ORF) of strains BJ, LaSota, HB and Yucaipa was inserted into the rSG10 backbone in place of the corresponding rSG10 sequence
The HA positive allantoic fluids were used for the isolation of viral RNA, followed by sequence analysis of an reverse transcription (RT)-PCR fragment to ensure the presence of the intended HN gene

Summary

Introduction

Newcastle disease (ND) is a constant threat to the poultry industry worldwide and has caused severe economic losses. The causative pathogen is Newcastle disease virus (NDV), which is a member of the genus Avulavirus in the family Paramyxoviridae (Mayo, 2002). NDV strains are classified into three major pathotypes: lentogenic, mesogenic, and velogenic, based on their pathogenicity in chickens. NDV can be classified into two classes based on genome length and the sequence of the F gene. Class II can be further divided into nine genotypes (Munir et al, 2012). Genotype VII NDVs are the predominant strains isolated throughout the world in recent years (Miller et al, 2009).

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Conclusion