The ability to read and interpret the sequence of DNA is a foundational technology that has transformed modern biology and medicine. By unlocking the genetic blueprints of organisms, scientists can understand the mechanisms of disease, track pathogens, and improve crop yields. Continuous innovation in sequencing platforms has focused on increasing speed, reducing cost, and enhancing data accuracy. DNBSEQ is one such breakthrough technology that has significantly impacted the landscape of next-generation sequencing.
Defining DNBSEQ Technology
DNBSEQ represents a proprietary sequencing method developed by MGI, a life science company. The name is an acronym for DNA Nanoball Sequencing, which points directly to the core innovation. DNBSEQ utilizes a different approach to preparing and reading DNA compared to methods that rely on bridge amplification clusters. The central feature is the use of DNA Nanoballs (DNBs), which are highly condensed, single-stranded DNA molecules created before sequencing.
The core innovation involves eliminating the Polymerase Chain Reaction (PCR) step from the on-chip amplification process. Instead, the technique creates these nanoballs off-chip and loads them onto a patterned array. This change allows DNBSEQ to offer distinct performance characteristics, particularly concerning sequencing fidelity and data output density. The technology integrates DNA circularization, the nanoball preparation process, a patterned array flow cell, and a specific sequencing chemistry known as Combinatorial Probe-Anchor Synthesis (cPAS).
The Mechanics of DNB Formation
DNB formation begins with fragmenting the original double-stranded DNA sample into smaller segments. Specific adapter sequences are ligated to the ends of these fragments, which are then denatured into single strands. A splint oligonucleotide is used to circularize the single-stranded DNA molecule, forming a nicked circle.
This circular molecule serves as the template for generating the nanoball through Rolling Circle Amplification (RCA). RCA is an isothermal process that uses a polymerase to continuously synthesize new copies of the circular template, creating a long, single-stranded DNA concatemer. This concatemer is a head-to-tail repetition of the original DNA fragment sequence, containing hundreds of identical copies.
The long, repetitive DNA strand folds and condenses into a compact DNB, typically around 200 nanometers in diameter. Because all copies within the DNB derive from a single original circular template, the amplification error rate is significantly reduced compared to exponential PCR methods. These DNBs are then deposited onto a patterned array flow cell, binding specifically to pre-etched spots. The sequencing reaction uses Combinatorial Probe-Anchor Synthesis (cPAS), where fluorescently labeled probes are incorporated stepwise to determine the sequence of bases.
Key Performance Advantages
DNB technology offers several performance benefits, starting with enhanced accuracy of the resulting sequence data. Since each DNB contains hundreds of identical copies of the template, the sequencing instrument reads the signal from a highly redundant structure. This built-in redundancy acts as error correction, minimizing random errors introduced during synthesis or imaging through the consensus reading of multiple copies.
This unique amplification method also leads to significantly reduced duplication rates in whole-genome and exome sequencing. Compared to PCR-based methods, the linear amplification of RCA minimizes error accumulation and reduces “index hopping,” where multiplexed samples are incorrectly assigned. Pairing DNBSEQ with PCR-free library preparation methods further reduces insertion and deletion (indel) errors, improving variant detection fidelity.
The combination of DNBs and a patterned array contributes to exceptional cost-effectiveness and high throughput. The patterned array is a specialized flow cell etched with millions of uniformly spaced binding sites, allowing for a higher density of sequencing reactions per unit area. Since DNBs are highly condensed and precisely loaded, the system processes massive amounts of data in a single run. This leads to lower reagent consumption and a reduced cost per sequenced base, making large-scale population sequencing projects more accessible.
Current Uses in Research and Medicine
DNBSEQ technology is widely utilized across large-scale genomic research and targeted clinical diagnostics. Its high-throughput capacity and cost-efficiency are well-suited for major national and international genome projects requiring the sequencing of thousands of human whole genomes. Researchers globally employ the technology for deep sequencing applications, including whole-exome sequencing and transcriptomics.
DNBSEQ supports diverse applications across multiple sectors:
- Agrigenomics research, using large-scale genotyping and gene expression analysis to improve livestock and crop varieties.
- Environmental and public health fields, such as metagenomics for studying microbial communities and disease surveillance.
- Clinical diagnostics, particularly for non-invasive testing and oncology.
- Non-invasive prenatal testing (NIPT), which analyzes fetal DNA in the mother’s blood to screen for chromosomal abnormalities.
- Cancer panel sequencing and tumor profiling, leveraging sequencing depth to detect somatic mutations and assist treatment decisions.