Comparative Virus-Host Protein Interactions of the Bluetongue Virus NS4 Virulence Factor.

Aurore Fablet,Corinne Sailleau,Damien Vitour,Grégory Caignard,Cindy Kundlacz,Juliette Dupré,Edouard Hirchaud,Lydie Postic,Stéphan Zientara,Emmanuel Bréard

doi:10.3390/v14020182

Abstract

Bluetongue virus (BTV) is the etiologic agent of a non-contagious arthropod-borne disease transmitted to wild and domestic ruminants. BTV induces a large panel of clinical manifestations ranging from asymptomatic infection to lethal hemorrhagic fever. Despite the fact that BTV has been studied extensively, we still have little understanding of the molecular determinants of BTV virulence. In our report, we have performed a comparative yeast two-hybrid (Y2H) screening approach to search direct cellular targets of the NS4 virulence factor encoded by two different serotypes of BTV: BTV8 and BTV27. This led to identifying Wilms’ tumor 1-associated protein (WTAP) as a new interactor of the BTV-NS4. In contrast to BTV8, 1, 4 and 25, NS4 proteins from BTV27 and BTV30 are unable to interact with WTAP. This interaction with WTAP is carried by a peptide of 34 amino acids (NS422−55) within its putative coil-coiled structure. Most importantly, we showed that binding to WTAP is restored with a chimeric protein where BTV27-NS4 is substituted by BTV8-NS4 in the region encompassing residue 22 to 55. We also demonstrated that WTAP silencing reduces viral titers and the expression of viral proteins, suggesting that BTV-NS4 targets a cellular function of WTAP to increase its viral replication.

Highlights

Bluetongue virus (BTV) is the etiological agent of the Bluetongue disease, a noncontagious arbovirus that affects a wide range of wild and domestic ruminants
To identify cellular partners of BTV-NS4, a cDNA library originating from cattle was screened by Y2H using full-length NS4 viral proteins from two serotypes
Total of 288 positive [His+] yeast colonies were recovered from these two screens (206 and 82 clones for BTV8-NS4 and BTV27-NS4, respectively) and cellular prey proteins were identified by cDNA amplification, sequencing and multi-parallel BLAST analysis

Summary

Introduction

Bluetongue virus (BTV) is the etiological agent of the Bluetongue disease, a noncontagious arbovirus that affects a wide range of wild and domestic ruminants It is transmitted by blood-feeding midges of the genus Culicoides. Since 2008, progress in molecular diagnosis and high-throughput sequencing approach ( generation sequencing) have led to the discovery of an increased number of new strains within serotypes and new serotypes of BTV. These newly identified BTVserotypes are characterized by a low (sometimes even an absence of) pathology/virulence, their capacity to infect only small ruminants such as goats and, for some of them, their direct transmission [2,3]. This non-classical group of BTV serotypes (BTV25-36) is named “atypical” BTVs, distinct from the classical BTV1–24

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