The BTV genome encodes also 3 non-structural proteins: NS1, NS2 and NS3/NS3a. NS1 and NS2 are highly expressed viral proteins and their multimers are morphological features of BTVinfected cells. Multimers of the NS1 protein form tubules (approximately 50 nm in diameter and up to 1000 nm in length) that appear to be linked to cellular cytopathogenicity [22] , while NS2 is the major component of the viral inclusion bodies. NS2 plays a key role in viral replication and assembly as it has a high affinity for single stranded RNA and possesses phosphohydrolase activity [23] . NS3/NS3a are glycosylated proteins involved in BTV exit. There are two isoforms of NS3: NS3 and NS3a with the latter lacking the N-terminal 13 amino acid residues [24] [25] [26] .