Abstract: An object of the present invention is to provide a method of efficiently constructing a gene delivery carrier having a favorable activity and expression efficiency of a protein expressed by a gene introduced by transformation. Moreover, an object of the present invention is to provide a pharmaceutical composition comprising a gene delivery carrier constructed by the construction method and a therapeutic agent for solid tumor comprising the resistant bacterium.

Abstract: The present invention provides a method for producing a cytosine deaminase (CD)-expressing, 5-fluorouracil (5-FU)-resistant microorganism which can grow in anaerobic tumor tissues, can express CD, and has a resistance to 5-FU at a concentration that is at least effective for antitumor activity. More specifically, the method is a method (A) comprising performing subculture or acclimation culture of a CD-expressing microorganism which can grow in anaerobic tumor tissues, in the presence of 5-fluorocytosine (5-FC), or a method (B) comprising (1) performing subculture or acclimation culture of a microorganism which can grow in anaerobic tumor tissues and does not express CD, in the presence of 5-FU to produce a 5-FU-resistant microorganism and (2) transforming the 5-FU-resistant microorganism by introducing a CD gene. The present invention also provides the CD-expressing, 5-FU-resistant microorganism and a pharmaceutical composition comprising the microorganism.

Abstract: The present invention provides a shuttle vector for a microorganism of the genus Bifidobacterium (BM) and Escherichia coli having a wide host range and a large copy number in BM and capable of highly expressing a desired protein when used as an expression vector; an expression vector capable of expressing a desired gene in BM by use of the shuttle vector; BM transformed with the expression vector; and an antitumor agent comprising the BM as an active ingredient. It comprises a pTB6-derived region portion comprising a replication origin (oriV)-repB region of pTB6 but not comprising MembB, MobA, OrfI, and oriT regions of pTB6 and an Escherichia coli-derived plasmid portion comprising a replication origin (Puc Ori) region of Escherichia coli but having deleted DNA encoding an N-terminal region of an ampicillin resistance gene (ampR) expression product ?-lactamase.

Abstract: The present invention provides a shuttle vector for a microorganism of the genus Bifidobacterium (BM) and Escherichia coli having a wide host range and a large copy number in BM and capable of highly expressing a desired protein when used as an expression vector; an expression vector capable of expressing a desired gene in BM by use of the shuttle vector; BM transformed with the expression vector; and an antitumor agent comprising the BM as an active ingredient. It comprises a pTB6-derived region portion comprising a replication origin (oriV)-repB region of pTB6 but not comprising MembB, MobA, OrfI, and oriT regions of pTB6 and an Escherichia coli-derived plasmid portion comprising a replication origin (oriC) region of Escherichia coli but having deleted DNA encoding an N-terminal region of an ampicillin resistance gene (ampR) expression product ?-lactamase, and constitute a shuttle vector for Escherichia coli with a BM having an average copy number of 6 to 30.

Abstract: The present invention provides a method for producing a cytosine deaminase (CD)-expressing, 5-fluorouracil (5-FU)-resistant microorganism which can grow in anaerobic tumor tissues, can express CD, and has a resistance to 5-FU at a concentration that is at least effective for antitumor activity. More specifically, the method is a method (A) comprising performing subculture or acclimation culture of a CD-expressing microorganism which can grow in anaerobic tumor tissues, in the presence of 5-fluorocytosine (5-FC), or a method (B) comprising (1) performing subculture or acclimation culture of a microorganism which can grow in anaerobic tumor tissues and does not express CD, in the presence of 5-FU to produce a 5-FU-resistant microorganism and (2) transforming the 5-FU-resistant microorganism by introducing a CD gene. The present invention also provides the CD-expressing, 5-FU-resistant microorganism and a pharmaceutical composition comprising the microorganism.

Abstract: An object of the present invention is to provide a method of efficiently constructing a gene delivery carrier having a favorable activity and expression efficiency of a protein expressed by a gene introduced by transformation. Moreover, an object of the present invention is to provide a pharmaceutical composition comprising a gene delivery carrier constructed by the construction method and a therapeutic agent for solid tumor comprising the resistant bacterium.