Patent ID: 8062850

Claim:
A process comprising: (a) contacting a recombinase agent with first, second and third nucleic acid primers to form first, second and third nucleoprotein primers, the third nucleic acid primer being an extension blocked primer that comprises one or more modified internal residues selected from the group consisting of tetrahydrofuran residue and deoxyribose residue; (b) contacting the first and second nucleoprotein primers to a double stranded target nucleic acid thereby forming first and second double stranded structures, the first double stranded structure being formed from the first nucleoprotein primer and a first strand of the double stranded target nucleic acid at a portion of the first strand, and the second double stranded structure being formed from the second nucleoprotein primer and a second strand of the double stranded target nucleic acid at a portion of the second strand so that 3′ ends of the first and second nucleoprotein primers are oriented toward each other on the target nucleic acid molecule with a portion of the target nucleic acid molecule between the 3′ ends of the first and second nucleoprotein primers; (c) extending the 3′ ends of the first and second nucleoprotein primers with one or more polymerases and dNTP to generate a first amplified target nucleic acid with an internal region comprising the third portion of the target nucleic acid molecule between the 3′ ends of the first and second nucleoprotein primers; (d) contacting the first amplified target nucleic acid with the third nucleoprotein primer in the presence of a nuclease selected from the group consisting of E. coli Nfo, E. coli exonuclease III, and fpg to form a third double stranded structure at the third portion of the amplified target nucleic acid; the nuclease specifically cleaving the tetrahydrofuran or deoxyribose residue only after the formation of the third double stranded structure, and cleavage of the tetrahydrofuran or deoxyribose residue forming a third 5′ primer double stranded structure and a 3′ extension blocked primer double stranded structure; (e) extending the 3′ end of the third 5′ primer with one or more polymerases and dNTP to generate a second double stranded amplified nucleic acid which comprises the first nucleic acid primer and the third 5′ primer; (f) continuing the reaction through repetition of (b) through (e) until a desired degree of the second double stranded amplified nucleic acid is reached.