Isothermal Point Mutation Detection: Toward a First-Pass Screening Strategy for Multidrug-Resistant Tuberculosis

Area of Science:

• Biotechnology
• Molecular Diagnostics
• Genetics

Background:

• Point mutations are crucial biomarkers for disease classification, diagnosis, and clinical decision-making.
• Conventional methods like real-time PCR and DNA sequencing for point mutation detection are slow and equipment-intensive.
• Existing rapid isothermal amplification strategies, such as recombinase polymerase amplification (RPA), often lack specificity in discriminating point mutations.

Purpose of the Study:

• To develop a novel, highly specific isothermal DNA amplification strategy for accurate point mutation discrimination.
• To demonstrate the assay's utility in rapid identification of drug-resistant Mycobacterium tuberculosis.
• To showcase the potential for point-of-care application and broad clinical utility in disease screening.

Main Methods:

• A new strategy employing mismatched primers and a two-round enrichment process for isothermal DNA amplification.
• Application of the method using RPA for detecting drug-resistant Mycobacterium tuberculosis.
• Adaptation of the assay onto a low-cost 3D-printed isothermal device for real-time analysis.

Main Results:

• The novel assay achieved exquisite point mutation discrimination with isothermal amplification.
• Demonstrated rapid and specific identification of drug-resistant Mycobacterium tuberculosis with picogram DNA input.
• The assay detected 10% point mutation loading, differentiated closely related mutants within 30 minutes, and was validated for cancer-associated mutations.

Conclusions:

• The developed assay offers a sensitive, specific, and rapid method for point mutation detection using isothermal amplification.
• The strategy is adaptable for point-of-care applications, potentially reducing unnecessary therapy and healthcare costs.
• The generic applicability extends to various clinical settings for disease screening and phenotype categorization.