Abstract: An objective of the present invention is to provide an improved negative-strand RNA viral vector and a use thereof, the negative-strand RNA viral vector exhibiting transient high expression of genes loaded in the vector and enabling the rapid removal of the vector after said expression. It was discovered that by adding a micro-RNA target sequence to the NP, P, or L gene of a negative-strand RNA viral vector, it is possible to control the expression of the vector depending on the micro-RNA expressed by the introduction cell. In particular, when a micro-RNA target sequence was added to the NP or P gene, the expression of the vector decreased depending on the micro-RNA, and the removal of the vector was promoted, while the effect was reversed when a micro-RNA target sequence was added to the L gene. The vector can be applied in cell therapy and regenerative medicine and can be used as a therapeutic vector that targets cancer.

Abstract: The present invention provides novel donor polynucleotides formed by linking the two ends of a genomic fragment containing a cleavable site by a polynucleotide carrying a positive selection marker gene and a negative selection marker gene. Use of the donor polynucleotide makes it possible to modify only a target gene with avoiding the possibility of introducing mutations to sequences, called “off-target”, which are other than the target sequence, by introducing cleavage in a homologous site of the donor polynucleotide without introducing cleavage in a target gene locus.