Improved multiple displacement amplification (iMDA) and ultraclean reagents

Area of Science:

• Genomics
• Molecular Biology
• Biotechnology

Background:

• Next-generation sequencing requires nanogram to microgram DNA quantities, posing challenges for low-cell samples.
• Whole genome amplification (WGA) methods are needed for unbiased, contamination-free genomic analysis of limited samples.

Purpose of the Study:

• To develop and optimize a whole genome amplification protocol (iMDA) for low-DNA samples.
• To create DNA-free reagents and consumables to prevent exogenous DNA contamination.

Main Methods:

• Developed ethylene oxide treatment for DNA-free consumables and qPCR validation.
• Implemented ion exchange chromatography, filtration, and lot testing for reagent purity.
• Enhanced multiple displacement amplification (iMDA) with a second strand-displacing DNA polymerase, improved buffers, and reaction conditions.

Main Results:

• iMDA with DNA-free reagents significantly improved amplification efficiency and accuracy for low-DNA specimens.
• iMDA demonstrated superior read mapping (>99%) compared to commercial kits (0.02%) using 10 fg bacterial DNA.
• iMDA achieved comparable genomic coverage (≥1X and ≥5X) to direct sequencing, ensuring balance and representation.

Conclusions:

• The iMDA protocol combined with DNA-free consumables substantially enhances sequencing of low-DNA samples.
• iMDA offers broad applications in metagenomics, diagnostics, forensics, single-cell genomics, and ancient DNA analysis.