Abstract: An antiviral protein having an amino acid sequence represented by sequence No. 8 of a Sequence Listing is disclosed. The protein is obtained such that cysteine residues in the basic protein (MAP) obtained from Mirabilis jalapa and having antiviral activity are substituted with serine residues. More specifically, a MAP gene in which codons encoding cysteines are substituted with codons encoding serines is prepared, and this gene is integrated in a MAP secretion vector. This vector is introduced into a host to express the gene, thereby obtaining the antiviral protein. This protein retains MAP advantages as a toxic protein and has higher protein synthesis inhibition activity than that of MAP, and almost equal to that of a lysine A chain.

Abstract: A method for producing MAP utilizing a gene which is formed by combining a gene coding for E.coli outer membrane protein OmpA signal peptide upstream of MAP gene as a foreign gene. In this method, said gene is inserted in a plasmid having E.coli expression systems and the recombinant plasmid obtained is introduced into E.coli for transformation.