Polymerase chain reaction and Qβ replicase amplification

Abstract

The polymerase chain reaction (PCR) and Qβ replicase are two methods in which nucleic acid polymerases are used for amplification. Although these approaches share many similar problems concerning target contamination and probe specificity, they differ dramatically in their mechanisms of action and modes of application. The PCR method amplifies target sequences between two priming oligonucleotides and in essence amplifies a portion of the analyte. Qβ replicase, on the other hand, amplifies a specific template molecule hybridized to target sequences and therefore amplifies a signal component of the system. For this reason, Qβ replicase amplification has applications in areas other than for the detection of nucleic acid sequences. The requirements for application and the advantages of both PCR and Qβ replicase amplification are reviewed.