Multiple Routes of Bluetongue Virus Egress

Abstract

Bluetongue virus (BTV) is an arthropod-borne virus infecting livestock. Its frequent emergence in Europe and North America had caused significant agricultural and economic loss. BTV is also of scientific interest as a model to understand the mechanisms underlying non-enveloped virus release from mammalian and insect cells. The BTV particle, which is formed of a complex double-layered capsid, was first considered as a lytic virus that needs to lyse the infected cells for cell to cell transmission. In the last decade, however, a more in-depth focus on the role of the non-structural proteins has led to several examples where BTV particles are also released through different budding mechanisms at the plasma membrane. It is now clear that the non-structural protein NS3 is the main driver of BTV release, via different interactions with both viral and cellular proteins of the cell sorting and exocytosis pathway. In this review, we discuss the most recent advances in the molecular biology of BTV egress and compare the mechanisms that lead to lytic or non-lytic BTV release.

Inhibition of the IFN Response by Bluetongue Virus: The Story So Far

“…BTV-NS3 is the main viral protein involved in virion egress in insect and mammalian cells ( Hyatt et al, 1993 ; Beaton et al, 2002 ; Labadie et al, 2020 ). NS3 is a transmembrane protein that is likely synthesized in the ER and traffics through the Golgi apparatus to reach the plasma membrane ( Wu et al, 1992 ; Bansal et al, 1998 ; Bhattacharya et al, 2015 ; Labadie et al, 2020 ). NS3 C-terminal region interacts with the outer BTV capsid protein VP2 which allows virion transport to the cell surface ( Celma and Roy, 2009 ).…”

Identification of a BTV-Strain-Specific Single Gene That Increases Culicoides Vector Infection Rate

“…BTV is a non-enveloped virus with a segmented double-stranded RNA (dsRNA) genome, belonging to the Orbivirus genus within the Reoviridae family. Ten linear genome segments (Seg-1 to Seg-10) encode for seven structural (VP1–VP7) and five non-structural (NS1, NS2, NS3/NS3A, NS4 and NS5) proteins [ 16 , 17 , 18 ]. The outer capsid of the BTV particle is formed of VP2 and VP5, which allow for membrane attachment and penetration.…”

“…The BTV core is composed of two structural proteins (VP3 and VP7), and it encloses transcription complexes (VP1, VP4 and VP6) in addition to the viral genome. The non-structural proteins play a key role in virus replication, maturation and exit from infected cells [ 16 , 17 , 18 ].…”

Pentavalent Disabled Infectious Single Animal (DISA)/DIVA Vaccine Provides Protection in Sheep and Cattle against Different Serotypes of Bluetongue Virus

“…The virion consists of a multilayered nonenveloped particle containing a 10-segmented genome of double-stranded RNAs (Seg-1 to -10) encoding seven structural proteins VP1-7 and at least four non-structural proteins NS1-4 [6][7][8][9]. NS3/NS3a protein encoded by Seg-10 is a multifunctional protein involved in virus release from the infected cell and immunosuppression of the ruminant host [10,11]. Seg-2 and Seg-6 codes for outer shell proteins VP2 and VP5, respectively, of which VP2 is the major serotype-specific protein inducing neutralizing antibodies (nAbs) [12].…”