Membrane Association of African Horsesickness Virus Nonstructural Protein NS3 Determines Its Cytotoxicity

Niekerk, Michelle Van; Smit, Carel C.; Fick, W; Staden, Vida van; Huismans, H.

doi:10.1006/viro.2000.0709

Cited by 20 publications

(14 citation statements)

References 31 publications

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“…3 ) ( 36 ). NS3/NS3a of AHSV has been associated with virulence and viremia ( 52 , 53 ), and virulent BTV8 without NS3/NS3a is not virulent and strongly reduced in viremia ( 37 ). Based on these in vitro similarities, we hypothesize that virulent AHSV lacking NS3/NS3a is not virulent in equids.…”

Section: Discussionmentioning

confidence: 99%

VP2 Exchange and NS3/NS3a Deletion in African Horse Sickness Virus (AHSV) in Development of Disabled Infectious Single Animal Vaccine Candidates for AHSV

Water¹,

Gennip²,

Potgieter

et al. 2015

J Virol

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African horse sickness virus (AHSV) is a virus species in the genus Orbivirus of the family Reoviridae. There are nine serotypes of AHSV showing different levels of cross neutralization. AHSV is transmitted by species of Culicoides biting midges and causes African horse sickness (AHS) in equids, with a mortality rate of up to 95% in naive horses. AHS has become a serious threat for countries outside Africa, since endemic Culicoides species in moderate climates appear to be competent vectors for the related bluetongue virus (BTV). To control AHS, live-attenuated vaccines (LAVs) are used in Africa. We used reverse genetics to generate “synthetic” reassortants of AHSV for all nine serotypes by exchange of genome segment 2 (Seg-2). This segment encodes VP2, which is the serotype-determining protein and the dominant target for neutralizing antibodies. Single Seg-2 AHSV reassortants showed similar cytopathogenic effects in mammalian cells but displayed different growth kinetics. Reverse genetics for AHSV was also used to study Seg-10 expressing NS3/NS3a proteins. We demonstrated that NS3/NS3a proteins are not essential for AHSV replication in vitro. NS3/NS3a of AHSV is, however, involved in the cytopathogenic effect in mammalian cells and is very important for virus release from cultured insect cells in particular. Similar to the concept of the bluetongue disabled infectious single animal (BT DISA) vaccine platform, an AHS DISA vaccine platform lacking NS3/NS3a expression was developed. Using exchange of genome segment 2 encoding VP2 protein (Seg-2[VP2]), we will be able to develop AHS DISA vaccine candidates for all current AHSV serotypes.IMPORTANCE African horse sickness virus is transmitted by species of Culicoides biting midges and causes African horse sickness in equids, with a mortality rate of up to 95% in naive horses. African horse sickness has become a serious threat for countries outside Africa, since endemic Culicoides species in moderate climates are supposed to be competent vectors. By using reverse genetics, viruses of all nine serotypes were constructed by the exchange of Seg-2 expressing the serotype-determining VP2 protein. Furthermore, we demonstrated that the nonstructural protein NS3/NS3a is not essential for virus replication in vitro. However, the potential spread of the virus by biting midges is supposed to be blocked, since the in vitro release of the virus was strongly reduced due to this deletion. VP2 exchange and NS3/NS3a deletion in African horse sickness virus were combined in the concept of a disabled infectious single animal vaccine for all nine serotypes.

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Section: Discussionmentioning

confidence: 99%

VP2 Exchange and NS3/NS3a Deletion in African Horse Sickness Virus (AHSV) in Development of Disabled Infectious Single Animal Vaccine Candidates for AHSV

Water¹,

Gennip²,

Potgieter

et al. 2015

J Virol

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“…The AHSV NS3 gene is the second most variable after the segment encoding VP2 [104], although this is not true of all orbiviruses [50]. Because NS3 is associated with the membrane of infected cells and it is relatively exposed to the host immune system, its high variability may be partially due to selective pressure to avoid immune recognition [90].…”

Section: The Ahsv Transmission Cyclementioning

confidence: 99%

Adaptive strategies of African horse sickness virus to facilitate vector transmission

et al. 2008

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African horse sickness virus (AHSV) is an orbivirus that is usually transmitted between its equid hosts by adult Culicoides midges. In this article, we review the ways in which AHSV may have adapted to this mode of transmission. The AHSV particle can be modified by the pH or proteolytic enzymes of its immediate environment, altering its ability to infect different cell types. The degree of pathogenesis in the host and vector may also represent adaptations maximising the likelihood of successful vectorial transmission. However, speculation upon several adaptations for vectorial transmission is based upon research on related viruses such as bluetongue virus (BTV), and further direct studies of AHSV are required in order to improve our understanding of this important virus.

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“…The extruded transcripts, in turn, function as templates for the synthesis of viral proteins and also act as templates for the synthesis of genomic dsRNA following their encapsidation in progeny viral cores. 6,7 Although a combination of mutagenesis and re-expression of AHSV proteins in heterologous hosts has allowed progress to be made regarding the structure-function relationships of selected AHSV proteins, [8][9][10][11][12][13] definitive roles for many of these proteins in the context of a replicating virus remain unresolved. Indeed, a major obstacle to studies aimed at understanding AHSV biology has been the inability to genetically manipulate the segmented dsRNA viral genome.…”

Section: Introductionmentioning

confidence: 99%

Directed genetic modification of African horse sickness virus by reverse genetics

et al. 2015

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African horse sickness virus (AHSV), a member of the Orbivirus genus in the family Reoviridae, is an arthropod-transmitted pathogen that causes a devastating disease in horses with a mortality rate greater than 90%. Fundamental research on AHSV and the development of safe, efficacious vaccines could benefit greatly from an uncomplicated genetic modification method to generate recombinant AHSV. We demonstrate that infectious AHSV can be recovered by transfection of permissive mammalian cells with transcripts derived in vitro from purified AHSV core particles. These findings were expanded to establish a genetic modification system for AHSV that is based on transfection of the cells with a mixture of purified core transcripts and a synthetic T7 transcript. This approach was applied successfully to recover a directed cross-serotype reassortant AHSV and to introduce a marker sequence into the viral genome. The ability to manipulate the AHSV genome and engineer specific mutants will increase understanding of AHSV replication and pathogenicity, as well as provide a tool for generating designer vaccine strains.

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Membrane Association of African Horsesickness Virus Nonstructural Protein NS3 Determines Its Cytotoxicity

Cited by 20 publications

References 31 publications

VP2 Exchange and NS3/NS3a Deletion in African Horse Sickness Virus (AHSV) in Development of Disabled Infectious Single Animal Vaccine Candidates for AHSV

VP2 Exchange and NS3/NS3a Deletion in African Horse Sickness Virus (AHSV) in Development of Disabled Infectious Single Animal Vaccine Candidates for AHSV

Adaptive strategies of African horse sickness virus to facilitate vector transmission

Directed genetic modification of African horse sickness virus by reverse genetics

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