Nicking and extension amplification reaction for the exponential amplification of nucleic acids
View Patent ↗The invention is in general directed to the rapid exponential amplification of short DNA or RNA sequences at a constant temperature.
1. A method for amplifying a target nucleotide sequence comprising:
(a) obtaining, from an animal, plant, or food, a sample comprising a target nucleic acid, the target nucleic acid comprising the target nucleotide sequence,
(b) without first subjecting the target nucleic acid to a thermal denaturation step associated with amplification of the target nucleotide sequence, combining, in a single step, the obtained sample directly with an amplification reagent mixture to form a reaction mixture or diluting the obtained sample and combining, in a single step, the diluted sample with an amplification reagent mixture to form a reaction mixture, in either case, the amplification reagent mixture being free of bumper primers and comprising:
(i) a polymerase,
(ii) a forward template nucleic acid comprising a 5′ portion that is non-complementary to the target nucleic acid sequence and contains a nicking site and a 3′ template recognition region that hybridizes to the target nucleic acid sequence,
(iii) a reverse template nucleic acid comprising a 5′ portion that is non-complementary to the target nucleic acid sequence and contains a nicking site and a 3′ recognition region that hybridizes to the target nucleic acid sequence, and
(iv) one or more nicking enzymes;
(c) subjecting the reaction mixture formed by the step of combining to essentially isothermal conditions to amplify the target nucleotide sequence without the assistance of bumper primers, wherein amplification is performed, in the presence of the one or more nicking enzymes, by multiple cycles of the polymerase extending the reverse template nucleic acid along the target nucleotide sequence and extending the forward template nucleic acid along the complement of the target nucleotide sequence, thereby producing a double-stranded nucleic acid amplification product comprising first and second double-stranded nicking sites spaced apart by the target nucleotide sequence;
and
(d) detecting the amplified target nucleotide sequence in real time within 10 minutes of subjecting the reaction mixture formed by the step of combining to essentially isothermal conditions, wherein:
(i) the target nucleotide sequence is between 20 and 40 nucleotides in length; and
(ii) the target nucleotide sequence is amplified 1E+6-fold or more in about ten minutes.
2. The method of claim 1 , wherein the forward template recognition region is 8-15 nucleotides long and the reverse template recognition region is 8-15 nucleotides long.
3. The method of claim 1 , wherein the target nucleotide sequence comprises from 1 to 5 nucleotides more than the sum of the nucleotides of the forward template recognition region and the reverse template recognition region.
4. The method of claim 3 , wherein the target nucleotide sequence comprises one nucleotide more than the sum of the nucleotides of the forward template recognition region and the reverse template recognition region.
5. The method of claim 3 , wherein the target nucleotide sequence comprises two nucleotides more than the sum of the nucleotides of the forward template recognition region and the reverse template recognition region.
6. The method of claim 3 , wherein the target nucleotide sequence comprises three nucleotides more than the sum of the nucleotides of the forward template recognition region and the reverse template recognition region.
7. The method of claim 1 , wherein the target nucleic acid is double-stranded DNA.
8. The method of claim 1 , wherein the target nucleic acid is single-stranded DNA.
9. The method of claim 1 , wherein the target nucleic acid is RNA.
10. The method of claim 1 , wherein the target nucleic acid is selected from the group consisting of genomic DNA, plasmid DNA, viral DNA, mitochondrial DNA, cDNA, synthetic double-stranded DNA and synthetic single-stranded DNA.
11. The method of claim 1 , wherein the target nucleic acid is selected from the group consisting of messenger RNA, viral RNA, ribosomal RNA, transfer RNA, micro RNA, micro RNA precursor, and synthetic RNA.
12. The method of claim 1 , wherein the polymerase is a thermophilic polymerase.
13. The method of claim 12 , wherein the polymerase is selected from the group consisting of Bst (large fragment) and 9 0 N.
14. The method of claim 13 , wherein the polymerase is Bst (large fragment).
15. The method of claim 1 , wherein the one or more nicking enzyme are selected from the group consisting of Nt.BspQI, Nb.BbvCi, Nb.BsmI, Nb.BsrDI, Nb.BtsI, Nt.AlwI, Nt.BbvCI, Nt.BstNBI, Nt.CviPII, Nb.Bpu10I, Nt.BspD6I, and Nt.Bpu10I.
16. The method of claim 1 , wherein the forward template nucleic acid is provided at the same concentration as the reverse template nucleic acid.
17. The method of claim 1 , wherein the ratio of the forward template nucleic acid to the reverse template nucleic acid is between 1:100 and 100:1.
18. The method of claim 1 , wherein two or more polymerases are combined.
19. The method of claim 18 , wherein at least one of the polymerases comprises reverse transcriptase activity.
20. The method of claim 1 , wherein the temperature of the substantially isothermal conditions is between 54° C. and 60° C.
21. The method of claim 20 , wherein the temperature of the substantially isothermal conditions is between 56° C. and 58° C.
22. The method of claim 1 , wherein the amplification is conducted for 1 to 10 minutes.
23. The method of claim 1 , wherein the amplification is conducted for 1 to 20 minutes.
24. The method of claim 1 , wherein said amplification product is detected by a detection method selected from the group consisting of fluorescence, intercalating dye detection, fluorescence resonance energy transfer (FRET), molecular beacon detection, and incorporation of labeled nucleotides.
25. The method of claim 1 , wherein at least two different target nucleotide sequences are amplified.
26. The method of claim 1 , wherein at least one of the forward template nucleic acid and reverse template nucleic acid comprises a spacer, blocking group, a modified nucleotide or combination thereof.
27. The method of claim 1 , wherein the target nucleotide sequence is amplified 1E+6-fold or more in about five minutes.
28. The method of claim 1 , wherein the target nucleotide sequence is amplified 1E+6-fold or more in about 2.5 minutes.
29. The method of claim 1 , wherein the target nucleotide sequence is amplified 1E+7-fold or more in about five minutes.
30. The method of claim 1 , wherein the target nucleotide sequence is amplified 1E+8-fold or more in about five minutes.
31. The method of claim 1 , wherein the target nucleotide sequence is amplified 1E+9-fold or more in about five minutes.
32. A method for amplifying a target nucleotide sequence comprising:
(a) obtaining, from an animal, plant, or food, a sample comprising a target nucleic acid, the target nucleic acid comprising the target nucleotide sequence,
(b) without first subjecting the target nucleic acid to a thermal denaturation step associated with amplification of the target nucleotide sequence, combining, in a single step, the obtained sample directly with an amplification reagent mixture to form a reaction mixture or diluting the obtained sample and combining, in a single step, the diluted sample with an amplification reagent mixture to form a reaction mixture, in either case, the amplification reagent mixture being free of bumper primers and comprising:
(i) a polymerase,
(ii) a forward template nucleic acid comprising a 5′ portion that is non-complementary to the target nucleic acid sequence and contains a nicking site and a 3′ template recognition region that hybridizes to the target nucleic acid sequence, and
(iii) a reverse template nucleic acid comprising a 5′ portion that is non-complementary to the target nucleic acid sequence and contains a nicking site and a 3′ template recognition region that hybridizes to the target nucleic acid sequence, and
(iv) one or more nicking enzymes;
(c) subjecting the reaction mixture formed by the step of combining to essentially isothermal conditions to amplify the target nucleotide sequence without the assistance of bumper primers, thereby generating, in the presence of the nicking enzymes, a double-stranded nucleic acid product comprising first and second double-stranded nicking sites spaced apart by the target nucleotide sequence; and
(d) detecting amplified target nucleotide sequence in real time within 10 minutes of subjecting the reaction mixture formed by the step of combining to essentially isothermal conditions,
wherein:
the target nucleotide sequence is amplified 1E+6-fold or more in about ten minutes.
33. The method of claim 1 or 32 , wherein the sample is obtained from an animal and is blood, mucus, sputum, saliva, tears, feces or urine of the animal.
34. The method of claim 33 , wherein the sample is obtained from an animal and is mucus, sputum, or saliva of the animal.
35. The method of claim 1 or 32 , wherein the sample is obtained from an animal and the animal is a human.
36. The method of claim 1 or 32 , wherein the sample is obtained from an animal and the target nucleic acid is a target nucleic acid of an animal pathogen.
37. The method of claim 36 , wherein the animal pathogen is a single-stranded DNA virus, double-stranded DNA virus, or single-stranded RNA virus.
38. The method of claim 36 , wherein the animal pathogen is a bacterium.