Expression of bluetongue virus serotype 17 NS1 protein from a cloned gene

A full-length copy of the coding region of segment 6 from bluetongue virus (BTV) serotype 17 was constructed from five overlapping cDNA clones. The gene coding for the NS1 protein was cloned into an expression plasmid under the control of a bacteriophage T7 promoter and expressed both in vitro and in Escherichia coli BL21(DE3) cells which contain a T7 RNA polymerase gene in their chromosome. Expression in both systems resulted in the synthesis of a protein comigrating with NS1 and a minor polypeptide comigrating with another viral-induced protein, NS1a, sometimes seen in BTV-infected cells. The proteins induced in E. coli were synthesized to high levels as insoluble products.