Long-read sequencing services

Long-read (third-generation) sequencing reads DNA fragments of 10,000 to over one million bases continuously, where Illumina short-read NGS reads only about 150-300 bases. Those long reads resolve highly repetitive regions (centromeres, telomeres, segmental duplications), close the gaps short reads leave in reference genomes, and enable telomere-to-telomere de novo assembly. Two platform duopolists dominate: Oxford Nanopore (ONT), which passes a single DNA or RNA strand through a protein nanopore and reads the ionic-current changes, allowing direct sequencing of native DNA and RNA with simultaneous 5mC / 5hmC / m6A methylation detection and no PCR amplification; and PacBio SMRT, whose Zero-Mode Waveguides perform circular-consensus sequencing to produce HiFi reads roughly 15-20 kb long at greater than 99.9% accuracy (Q30). Services span de novo assembly, structural-variant detection, haplotype phasing, metagenomics and clinical genetics, regulated as IVD / LDT by the FDA and NMPA and under the EU IVDR. The six organizations in this projection span the two platforms (Oxford Nanopore, PacBio) and the service ecosystem (NextOmics, Genoscope, Broad Institute, SciLifeLab).

Key directions of long-read sequencing services:

1. Telomere-to-telomere de novo assembly: long reads close repeats and gaps that short reads cannot resolve.
2. Direct epigenetic detection: native 5mC / 5hmC / m6A without bisulfite conversion (ONT) or from polymerase kinetics (PacBio).
3. Structural-variant and clinical genetics: balanced translocations and repeat-expansion disorders undetectable by short reads.
4. Field and environmental metagenomics: portable MinION real-time ocean and soil surveillance (Genoscope).

Sectoral value chain#

[HMW DNA extraction] ──> [library prep] ──> [sequencing run] ──> [basecalling]
                                                                  │
                                                    (epigenetics + assembly)
                                                                  │
                                                                  ▼
[validated report] <─── [bioinformatics] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• nanopore-sequencing: direct-strand DNA/RNA through protein nanopores with AI basecalling (Dorado).
• smrt-sequencing: circular-consensus HiFi reads in Zero-Mode Waveguides (PacBio Revio).
• genome-assembly: OLC assemblers (Flye, Hifiasm, Minimap2) for de novo assembly and phasing.

The stack combines protein-engine nanopores, nanofabricated optical chips and specialized long-read assembly algorithms.

1. Nanopore sequencing (ONT):
   • an engineered protein channel (R10.4.1, a CsgG mutant) sits in a synthetic membrane; a motor helicase ratchets single-stranded DNA through at roughly 400 bases per second, and the ionic-current trace is decoded into bases by a deep-learning basecaller (Dorado), reading native DNA, RNA and methylation directly.
2. SMRT circular-consensus sequencing (PacBio):
   • Zero-Mode Waveguides (~100 nm wells) each immobilize a single polymerase; a circular SMRTbell template is read repeatedly and consensus-collapsed into HiFi reads at Q30 (>99.9%), and the new SPRQ-Nx chemistry drives HiFi human genomes below USD 300.
3. Assembly bioinformatics:
   • because long reads defeat de-Bruijn short-read assemblers, OLC assemblers take over — Flye for nanopore and Hifiasm for diploid/polyploid HiFi phasing — with Minimap2 for alignment, producing telomere-to-telomere assemblies.