Orbiviruses are double stranded RNA retroviruses of which the bluetongue virus is a member. The core of bluetongue virus (BTV) is a multienzyme complex composed of two major proteins (VP7 and VP3) and three minor proteins (VP1, VP4 and VP6) in addition to the viral genome. VP4 has been shown to perform all RNA capping activities and has both methyltransferase type 1 and type 2 activities associated with it.
Jiyao W et al.(2023). "The conserved domain database in 2023.",