What are the major isothermal amplification methods and their applications?

Isothermal amplification occurs at constant temperature without thermal cycling. LAMP (Loop-mediated isothermal amplification) uses 4-6 primers and Bst polymerase at 60-65C, producing cauliflower-like products detectable by turbidity or color change. RPA (Recombinase Polymerase Amplification) works at 37-42C using recombinase for strand invasion. NASBA amplifies RNA directly using reverse transcriptase, RNase H, and T7 RNA polymerase. HDA (Helicase Dependent Amplification) uses helicase for strand separation. Applications include point-of-care diagnostics, field testing, and resource-limited settings where thermocyclers are unavailable. CRISPR-based detection often incorporates isothermal preamplification.