Allelic-level resolution HLA typing is known to improve survival prognoses post Unrelated Donor (UD) Haematopoietic Stem Cell Transplantation (HSCT). Currently, many commonly used HLA typing methodologies are limited either due to the fact that ambiguity cannot be resolved or that they are not amenable to high-throughput laboratories. Pacific Biosciences’ Single Molecule Real-Time (SMRT) DNA sequencing technology enables sequencing of single molecules in isolation and has read-length capabilities to enable whole gene sequencing for HLA. DNA barcode technology labels samples with unique identifiers that can be traced throughout the sequencing process. The use of DNA barcodes means that multiple samples can…
The correct phasing of genetic variations is a key challenge for many applications of DNA sequencing. Allele-level resolution is strongly preferred for histocompatibility sequencing where recombined genes can exhibit different compatibilities than their parents. In other contexts, gene complementation can provide protection if deleterious mutations are found on only one allele of a gene. These problems are especially pronounced in immunological domains given the high levels of genetic diversity and recombination seen in regions like the Major Histocompatibility Complex. A new tool for analyzing Single Molecule, Real-Time (SMRT) Sequencing data – Long Amplicon Analysis (LAA) – can generate highly accurate,…
Sequence based typing (SBT) is considered the gold standard method for HLA typing. Current SBT methods are rather laborious and are prone to phase ambiguity problems and genotyping uncertainties. As a result, the NGS community is rapidly seeking to remedy these challenges, to produce high resolution and high throughput HLA sequencing conducive to a clinical setting. Today, second generation NGS technologies are limited in their ability to yield full length HLA sequences required for adequate phasing and identification of novel alleles. Here we present the use of single molecule real time (SMRT) sequencing as a means of determining full length/long…
We have produced an updated annotation of the Norway spruce genome on the basis of an in siliconormalised set of RNA-Seq data obtained from 1,529 samples and comprising 15.5 billion paired-end Illumina HiSeq reads complemented by 18Mbp of PacBio cDNA data (3.2M sequences). In addition to augmenting and refining the previous protein coding gene annotation, here we focus on the addition of long intergenic non-coding RNA (lincRNA) and micro RNA (miRNA) genes. In addition to non-coding loci, our analyses also identified protein coding genes that had been missed by the initial genome annotation and enabled us to update the annotation…
Introduction: Long-read sequencing has been applied successfully to assemble genomes and detect structural variants. However, due to high raw-read error rates (10-15%), it has remained difficult to call small variants from long reads. Recent improvements in library preparation and sequencing chemistry have increased length, accuracy, and throughput of PacBio circular consensus sequencing (CCS) reads, resulting in 10-20kb reads with average read quality above 99%. Materials and Methods: We sequenced a 12kb library from human reference sample HG002 to 18-fold coverage on the PacBio Sequel II System with three SMRT Cells 8M. The CCS algorithm was used to generate highly-accurate (average…
Interested to learn about pangenomes? Explore this guide to learn how they provide a more complete picture of the core genes of a given species and how that can provide better biological understanding.
Ulf Gyllensten speaks about advances in screening for HPV, his predictions for the widespread use of genome sequencing in the clinic, and applications using Single Molecule, Real-Time (SMRT) Sequencing for human genome studies.
In this AGBT 2017 poster, Ulf Gyllensten from Uppsala University presents two local reference genomes generated with PacBio and Bionano Genomics data. These assemblies include structural variation and repetitive regions that have been missed with previous short-read efforts, including some new genes not annotated in the human reference genome.
In this ASHG workshop presentation , Jonas Korlach, CSO of PacBio, walked attendees through recent product updates and the coming technology roadmap. The Sequel System 6.0 release offered major improvements to accuracy, throughput, structural variant calling, and large-insert libraries, he said, showing examples of 35 kb libraries. Looking ahead, Korlach said that the V2 express library preparation product should be available early in 2019, with the new 8M SMRT Cell being introduced sometime later.
In this SMRT Leiden 2020 Online Virtual Event presentation, Ida Hoijer of Uppsala University shares her research on developing a long-read sequencing-based method for detection of CRISPR-Cas9 off-target effects, along with a customized analysis pipeline. By applying an off-target sequencing (OTS) method on a human embryonic cell line, they detected 55 on- and off-target sites for three different gRNAs, including allele-specific off-targets. As the OTS approach finds off-targets that are difficult to predict using in silico or short-read based methods, it may become an important tool for genome editing.
At AGBT 2020, Adam Ameur from Uppsala University discussed the use of long-read PacBio sequencing to detect off-target results from CRISPR/Cas9 gene editing studies. His team uses HiFi reads from the Sequel II System to perform whole genome sequencing and figure out exactly where guide RNAs bind. In one example using a human embryonic kidney cell line, they found 55 off-target sites for three guide RNAs. Ameur’s group has already generated preliminary data on results from editing living cells.
In this SMRT Leiden 2020 Online Virtual Event presentation Pedro Oliveira of Mount Sinai shares his research on Clostridioides – a leading cause of nosocomial-acquired diarrhea and colitis across the developed world. In this study, Oliveira and coworkers performed the first comprehensive DNA methylome analysis of 36 human C. difficile isolates from a hospital setting using SMRT Sequencing and comparative epigenomics.
In this webinar, Adam Ameur of SciLifeLab at Uppsala University shares how he uses Single Molecule, Real-Time (SMRT) Sequencing applications for medical diagnostics and human genetics research, including sequencing of single genes and de novo assembly of human genomes as well as a new method for detection of CRISPR-Cas9 off-targets.
We tested extended-spectrum ß-lactamase producing bacteria from wild gulls (Larus spp.) sampled in 2009 for the presence of mcr-1. We report the detection of mcr-1 and describe genome characteristics of four Escherichia coli and one Klebsiella pneumoniae isolate from Spain and Portugal that also exhibited colistin resistance. Results represent the earliest evidence for colistin-resistant bacteria in European wildlife.Published 2019. This article is a U.S. Government work and is in the public domain in the USA.