From a molecular and structural virology perspective BTV is one of the best understood animal viruses. BTV is a member of the Orbivirus genus, within the Reoviridae family, and possesses a doublestranded RNA genome formed by 10 segments (Seg-1 to Seg-10) of approximately 19200 base pairs in total [1, 3] . Until now, the BTV genome has been shown to encode for 7 structural and 3 non-structural proteins. The BTV genome is packaged within a triple layered icosahedral protein capsid of approximately 90 nm in diameter [1, [7] [8] [9] [10] . The outer capsid of the virion is composed by 60 trimers of VP2 and 120 trimers of VP5 [11] and differences within this outer capsid define the 26 BTV serotypes which have been described so far [12, 13] . The outer capsid proteins, and VP2 in particular, stimulate virus neutralizing antibodies which in general protect only against the homologous serotype [14] . The internal core is formed by two layers, constituted by VP3 (subcore) and the immunodominant VP7 (intermediate layer) [7] . Three minor enzymatic proteins, VP1 (RNA dependent RNA polymerase), VP4 (capping enzyme and transmethylase) and VP6 (RNA dependent ATPase and helicase) are contained within the core that is transcriptionally active in infected cells [15] [16] [17] [18] [19] [20] [21] .