Inhibition of Orbivirus Replication by Fluvastatin and Identification of the Key Elements of the Mevalonate Pathway Involved

Abstract

Statin derivatives can inhibit the replication of a range of viruses, including hepatitis C virus (HCV, Hepacivirus), dengue virus (Flavivirus), African swine fever virus (Asfarviridae) and poliovirus (Picornaviridae). We assess the antiviral effect of fluvastatin in cells infected with orbiviruses (bluetongue virus (BTV) and Great Island virus (GIV)). The synthesis of orbivirus outer-capsid protein VP2 (detected by confocal immunofluorescence imaging) was used to assess levels of virus replication, showing a reduction in fluvastatin-treated cells. A reduction in virus titres of ~1.7 log (98%) in fluvastatin-treated cells was detected by a plaque assay. We have previously identified a fourth non-structural protein (NS4) of BTV and GIV, showing that it interacts with lipid droplets in infected cells. Fluvastatin, which inhibits 3-hydroxy 3-methyl glutaryl CoA reductase in the mevalonic acid pathway, disrupts these NS4 interactions. These findings highlight the role of the lipid pathways in orbivirus replication and suggest a greater role for the membrane-enveloped orbivirus particles than previously recognised. Chemical intermediates of the mevalonic acid pathway were used to assess their potential to rescue orbivirus replication. Pre-treatment of IFNAR(−/−) mice with fluvastatin promoted their survival upon challenge with live BTV, although only limited protection was observed.

The Combined Expression of the Nonstructural Protein NS1 and the N-Terminal Half of NS2 (NS2 1-180 ) by ChAdOx1 and MVA Confers Protection against Clinical Disease in Sheep upon Bluetongue Virus Challenge

“…Due to the lack of therapeutic treatments ( 11 , 12 ), vaccination against BTV constitutes the most effective prophylactic measure for BT control. Traditionally, vaccination strategies against this disease are based on conventional approaches, such as inactivated or live attenuated vaccines (LAVs).…”

Increased Clinical Signs and Mortality in IFNAR(−/−) Mice Immunised with the Bluetongue Virus Outer-Capsid Proteins VP2 or VP5, after Challenge with an Attenuated Heterologous Serotype

“…The interaction of BTV particles complexed with pre-existing antibodies could also lead to enhanced release of cytokines and endothelial cell death [10,11], resulting in increased severity of clinical signs. IFNAR (−/−) mice have previously been used as a model for studies of the protection induced by experimental orbivirus vaccines or potential antiviral molecules [32,39,[47][48][49][50][51]. The cross-protection that was observed in earlier studies after sequential vaccination (with live attenuated BTV vaccines) or infection with multiple BTV serotypes [52] may depend more on the cross-serotype reactivity of protective cell-mediated responses that have been demonstrated targeting BTV non-structural proteins [2], rather than any cross-serotype neutralising antibody responses, although we cannot rule out low-level cross neutralisation between strains containing closely related VP2 proteins [33].…”

Orbivirus NS4 Proteins Play Multiple Roles to Dampen Cellular Responses

“…IFNAR (-/-) mice represent a well-established model for studying orbivirus replication, vaccinology and assessment of antiviral molecules [ 36 , 45 , 46 , 47 , 48 , 49 , 50 ]. BTV replicates in these mice causing clinical signs.…”