Abstract: Contaminant viruses can be efficiently removed almost without losing the activity of protein by subjecting a plasma protein composition having a high risk of viral contamination to a treatment with a porous membrane having a pore size greater than a single-particle size of the virus, particularly by subjecting a plasma protein composition to a fractionation treatment by precipitation, before the porous membrane treatment. Particularly, a fibrinogen composition substantially free of non-enveloped viruses, Parvovirus among others, can be provided. By the application of the present invention, a safe plasma protein preparation free of viruses can be conveniently provided.

Abstract: Contaminant viruses can be efficiently removed almost without losing the activity of protein by subjecting a plasma protein composition having a high risk of viral contamination to a treatment with a porous membrane having a pore size greater than a single-particle size of the virus, particularly by subjecting a plasma protein composition to a fractionation treatment by precipitation, before the porous membrane treatment. Particularly, a fibrinogen composition substantially free of non-enveloped viruses, Parvovirus among others, can be provided. By the application of the present invention, a safe plasma protein preparation free of viruses can be conveniently provided.

Abstract: A DNA sequence of the yeast glyceraldehyde-3-phosphate dehydrogenase (GAP-DH) promoter and a process for preparing a heterologous protein utilizing said DNA sequence as a promoter are disclosed, said GAP-DH promoter comprising a region upstream of an initiator codon of the GAP-DH protein up to -164 bp as a minimum unit. Since the GAP-DH promoter is small in size, a physiologically active substance can be expressed in yeasts effectively and recombination of DNA can be simplified.

Abstract: A method of producing a heterologous protein in yeast is disclosed, which comprises transforming a yeast Saccharomyces cerevisiae with recombinant DNA comprising a promoter selected from the group consisting of a yeast promoter or a hybrid promoter derived from a yeast promoter, particularly a hybrid promoter containing the enhancer region of SV40 virus, and a gene coding for a heterologous protein such as HBsAg and Pre S-HBsAg, particularly full length Pre S-HBsAg culturing, the resulting transformed cells to express the gene coding the heterologous protein, and isolating the heterologous protein from the cultured medium. GAP-DH and PH05 promoters and miniaturized ones can be used as the yeast promoter. The expression of the full length Pre S-HBsAg is carried out in the same expression system as that for 2nd or 3rd Pre S-ABsAg.