Patent ID: 8067205

Claim:
A method for constructing a DNA vector having a cDNA synthesized from an mRNA, which method comprises the steps of: (i) annealing a double-stranded DNA primer and an mRNA mixture, wherein the double-stranded DNA primer consists of a first strand having a primer sequence and a second strand, and wherein the double-stranded DNA primer contains a replication origin or both a replication origin and a promoter for cDNA expression, (ii) preparing an mRNA/cDNA heteroduplex by synthesizing a first-strand cDNA primed with the primer sequence of the first strand of the double-stranded DNA primer using reverse transcriptase, (iii) circularizing the mRNA/cDNA heteroduplex by ligating the 3′ end of the first strand cDNA to the 5′ end of the first strand of the double-stranded DNA primer using T4 RNA ligase to form a circular mRNA/cDNA heteroduplex, and (iv) replacing the RNA in the mRNA/cDNA heteroduplex with a second-strand cDNA by synthesizing the second-strand cDNA with a DNA polymerase, thereby constructing the DNA vector having cDNA consisting of the first-strand cDNA and the second-strand cDNA.