Patent ID: 7914986

Claim:
Method to amplify nucleic acid sequence, comprising the steps of selecting a forward primer comprising a complementary sequence element B that is complementary to a sequence element on said nucleic acid sequence and hybridizes to said nucleic acid sequence, and said forward primer comprising a sequence element A that is not complementary to said nucleic acid sequence and situated upstream of the said complementary primer sequence element, the difference between the annealing temperatures on their respective complementary DNA sequences of the B element and the A and B element together, respectively, being greater than 5 degree Celsius, and selecting a reverse primer comprising a complementary sequence element B that is reverse complementary to a different sequence element downstream on said nucleic acid sequence than the forward primer and hybridizes to the complementary strand of said nucleic acid sequence, and said reverse primer comprising a sequence element A that is not complementary to said nucleic acid sequence and situated upstream of the said complementary primer sequence element, the difference between the annealing temperatures on their respective complementary DNA sequences of the B element and the A and B element together, respectively, being greater than 5 degree Celsius, and conducting a contamination detection reaction comprising one or several annealing steps followed by one or several polymerisation steps, where the forward and reverse primers are brought into contact with the DNA that is to be amplified in the presence of thermostable DNA polymerase, buffer, and deoxyribonucleotides commonly used in polymerase chain reactions, and an annealing temperature for the annealing steps is selected at which annealing temperature the A and B sequence will anneal to and form stable double helical structures with its complementary DNA sequence but the B sequence element alone will not anneal and form stable double helical structures with its complementary sequence, and conducting a target amplification reaction comprising one or several annealing steps followed by one or several polymerisation steps, where the forward and reverse primers are brought into contact with the DNA that is to be amplified in the presence of thermostable DNA polymerase, buffer, deoxynucleotides and all ingredients commonly used in polymerase chain reactions, and an annealing temperature for the annealing steps is selected at which annealing temperature the B sequence element alone will anneal and form stable double helical structures with its complementary sequence, and determining the absence or presence of a contamination with amplicon from previous polymerase chain amplification reactions with the forward and reverse primers by the absence or presence, respectively, of amplification product after the contamination detection reaction.