Elucidating the Role of CRISPR/Cas in Single-Step Isothermal Nucleic Acid Amplification Testing Assays

Area of Science:

• Molecular Biology
• Biotechnology
• Assay Development

Background:

• CRISPR/Cas systems combined with isothermal nucleic acid amplification offer novel, simple point-of-care diagnostic potential.
• Current research predominantly focuses on two-step assays, with limited investigation into integrated single-step CRISPR/Cas and amplification methods.
• Existing single-step assays often exhibit poor performance, highlighting a knowledge gap in their development and optimization.

Purpose of the Study:

• To systematically investigate and compare single-step CRISPR/Cas12a-assisted isothermal nucleic acid amplification assays.
• To identify optimal conditions for integrating CRISPR/Cas12a with recombinase polymerase amplification (RPA).
• To develop an improved single-step assay with enhanced performance characteristics.

Main Methods:

• Development and comparison of single-step assays using identical recombinase polymerase amplification (RPA) with varying CRISPR/Cas12a components.
• Systematic investigation of CRISPR/Cas12a concentration as a critical parameter.
• Evaluation of a protospacer adjacent motif (PAM)-free CRISPR/Cas12a-assisted RPA assay.

Main Results:

• CRISPR/Cas12a enhances signal amplification but can impede RPA efficiency.
• Optimal CRISPR/Cas12a concentration is crucial for mitigating RPA impediment and ensuring assay performance.
• The developed PAM-free CRISPR/Cas12a-assisted RPA assay demonstrated superior performance in design, signal, sensitivity, and speed compared to counterparts.
• A commercial Cas12a effector was successfully utilized, reducing cost but also signal intensity.

Conclusions:

• Optimizing CRISPR/Cas12a concentration is essential for successful single-step CRISPR-RPA assay development.
• The PAM-free CRISPR/Cas12a-assisted RPA assay represents a significant advancement in single-step assay design.
• These findings provide valuable insights for future development of CRISPR-based diagnostic assays.