One-Enzyme Reverse Transcription qPCR Using Taq DNA Polymerase

Area of Science:

• Molecular Biology
• Enzymology
• Virology

Background:

• Taq DNA polymerase is a well-established thermostable enzyme primarily used for Polymerase Chain Reaction (PCR).
• Despite its common use, Taq polymerase shares a superfamily with reverse transcriptases and has demonstrated latent reverse transcriptase activity.
• Previous research has indicated the potential for Taq polymerase to perform reverse transcription, but this activity has not been optimized for routine use.

Purpose of the Study:

• To optimize buffer and salt conditions to enhance the reverse transcriptase activity of Taq DNA polymerase.
• To establish Taq DNA polymerase as a single enzyme for Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR).
• To validate the utility of Taq-alone RT-qPCR assays for sensitive detection of viral genomic RNA.

Main Methods:

• Optimization of reaction buffers and salt concentrations to promote Taq DNA polymerase's reverse transcriptase function.
• Development of a one-enzyme RT-qPCR protocol using only Taq DNA polymerase.
• Application of the optimized Taq-alone RT-qPCR assays to detect SARS-CoV-2 viral genomic RNA using CDC N1, N2, and N3 TaqMan assays.

Main Results:

• Identified specific buffer and salt compositions that significantly enhance Taq DNA polymerase's reverse transcriptase activity.
• Demonstrated successful implementation of Taq-alone RT-qPCR assays, eliminating the need for a separate reverse transcriptase enzyme.
• Achieved sensitive detection of as low as 2 copies/µL of input viral genomic RNA in SARS-CoV-2 detection assays.

Conclusions:

• Taq DNA polymerase can be effectively utilized as a sole enzyme for RT-qPCR by optimizing reaction conditions.
• The development of Taq-alone RT-qPCR offers a simplified and potentially more cost-effective method for nucleic acid amplification and detection.
• This optimized Taq polymerase activity holds promise for rapid and sensitive diagnostics, particularly for viral RNA detection, including SARS-CoV-2.