Abstract: A method of purifying a recombinant fused protein characterized in that a recombinant fused protein, wherein a target protein has been fused with dockerin by genetic engineering techniques, is treated with a support having a cohesin domain immobilized thereon; and a method of producing a target protein characterized by comprising obtaining a recombinant fused protein having the target protein bound to dockerin with the use of an expression vector having a gene encoding the target protein and the dockerin inserted thereinto, subsequently purifying the recombinant fused protein by binding to a support having a cohesin domain immobilized thereon, and then eliminating the dockerin from the recombinant fused protein are disclosed. Using these methods, it becomes possible to provide an affinity purification technique with the use of specific binding whereby a high affinity and easy dissociation can be established without causing insolubilization or inactivation.

Abstract: For the expression of a foreign gene, a virus is provided in which at least a part of a cysteine protease gene present on a genome of a baculovirus has been deleted or substituted by a marker gene. A process is also disclosed for the formation of the virus. A transfer vector for the deletion of a cysteine protease gene is also described. This transfer vector comprises a DNA fragment of a nuclear polyhedrosis virus genome, in which at least a part of a cysteine protease gene has been substituted by a marker gene, and a plasmid vector fragment. Also disclosed is a process for the production of an economic protein.

Abstract: An economic protein can be produced by using silkworms. The silkworms are chilled, warmed, and then orally infected with a virus in which a gene coding the target protein has been inserted. The silkworms so infected are then raised, followed by the collection of the target protein from the silkworms.