The LORF5 Gene Is Non-essential for Replication but Important for Duck Plague Virus Cell-to-Cell Spread Efficiently in Host Cells.

Bingjie Shen ,Juan Huang,Qun Gao,Yunjiao Li,Mingshu Wang,Ying Wu,Renyong Jia,Yunya Liu,Xumin Ou,Mafeng Liu,Shun Chen,Anchun Cheng,Shaqiu Zhang,Qiao Yang,Di Sun,Sai Mao,Bin Tian,Dekang Zhu,Ling Zhang,Yanling Yu,Leichang Pan,Xinxin Zhao

doi:10.3389/fmicb.2021.744408

Abstract

Duck plague virus (DPV) can cause high morbidity and mortality in many waterfowl species within the order Anseriformes. The DPV genome contains 78 open reading frames (ORFs), among which the LORF2, LORF3, LORF4, LORF5, and SORF3 genes are unique genes of avian herpesvirus. In this study, to investigate the role of this unique LORF5 gene in DPV proliferation, we generated a recombinant virus that lacks the LORF5 gene by a two-step red recombination system, which cloned the DPV Chinese virulent strain (DPV CHv) genome into a bacterial artificial chromosome (DPV CHv-BAC); the proliferation law of LORF5-deleted mutant virus on DEF cells and the effect of LORF5 gene on the life cycle stages of DPV compared with the parent strain were tested. Our data revealed that the LORF5 gene contributes to the cell-to-cell transmission of DPV but is not relevant to virus invasion, replication, assembly, and release formation. Taken together, this study sheds light on the role of the avian herpesvirus-specific gene LORF5 in the DPV proliferation life cycle. These findings lay the foundation for in-depth functional studies of the LORF5 gene in DPV or other avian herpesviruses.

Highlights

Duck plague (DP), known as duck virus enteritis (DVE), is an acute, febrile, septic, and contagious disease in birds within Anseriformes
To determine the role of LORF5 gene in virus replication, a Duck plague virus (DPV) LORF5 mutant was generated on the basis of DPV CHvBAC, following the method of two-step Red recombination for constructing point mutations reported by Tischer et al (2010; Figure 1)
To confirm the abrogation of LORF5 gene, viral DNA was extracted for PCR analysis (Figure 2B) and positive bacterial artificial chromosome (BAC) clones were confirmed by restriction fragment length polymorphism (RFLP) analysis (Figure 2C) and Sanger sequencing

Summary

Introduction

Duck plague (DP), known as duck virus enteritis (DVE), is an acute, febrile, septic, and contagious disease in birds within Anseriformes (such as ducks, geese, and swans). Vaccines are considered the most effective means for preventing DP. Live attenuated vaccines of DP virus (DPV) have been used to treat this disease (Qi et al, 2009; Shen et al, 2010; Yang et al, 2010; Huang et al, 2014), and a variety of new effective vaccines have been developed in recent years (Lian et al, 2011; Yu et al, 2012; Sun et al, 2013), which efficiently control DP but have not completely eradicated it.

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