Jump to Main Content
Non-structural protein NS3/NS3a is required for propagation of bluetongue virus in Culicoides sonorensis
- Feenstra, Femke, Drolet, Barbara S., Boonstra, Jan, van Rijn, Piet A.
- Parasites & vectors 2015 v.8 no.476
- Bluetongue virus, Culicoides sonorensis, immunity, live vaccines, midges, phenotype, sheep, strains, viral nonstructural proteins, viremia, virulence, virus replication, viruses
- Background: Bluetongue virus (BTV) causes non-contagious haemorrhagic disease in ruminants and is transmitted by Culicoides spp. biting midges. BTV encodes four non-structural proteins of which NS3/NS3a is functional in virus release. NS3/NS3a is not essential for in vitro virus replication. However, deletion of NS3/NS3a leads to delayed virus release from mammalian cells and largely reduces virus release from insect cells. NS3/NS3a knockout BTV in sheep causes no viremia, but induces sterile immunity and is therefore proposed to be a Disabled Infectious Single Animal (DISA) vaccine candidate. In the absence of viremia, uptake of this vaccine strain by blood-feeding midges would be highly unlikely. Nevertheless, unintended replication of vaccine strains within vectors, and subsequent recombination or re-assortment resulting in virulent phenotypes and transmission is a safety concern of modified-live vaccines.