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Nanotrap particles can enhance present sequencing workflows of SARS-CoV-2

Researchers from Ceres Nanosciences, USA, have introduced a nanotrap enrichment workflow for capturing and concentrating extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particles from diagnostic and contrived samples.

This strategy enhances each column and magnetic bead-based RNA extraction protocols, offering important enhancements in sequencing outcomes on the Oxford Nanopore applied sciences (ONT) MinION sequencing platform. Sequencing output demonstrated considerably extra mapped viral reads, and 20-80% improved sequence protection from diagnostic samples with low virus titers.

Examine: Nanotrap Particles Enhance Nanopore Sequencing of SARS-CoV-2 and Different Respiratory Viruses. Picture Credit score: Unitone Vector/Shutterstock

The crew additionally demonstrated the identical strategy to complement two different respiratory viruses specifically Influenza A virus and respiratory syncytial virus, highlighting its potential to enhance real-time PCR and sequencing outcomes for respiratory viruses aside from SARS-CoV-2.


Steady genetic evolution of SARS-CoV-2 highlights the necessity to continuously determine and monitor the emergence of recent viral variants, and thus particularly calls for for quickly deployable correct sequencing applied sciences.

Right here, the ONT MinION sequencer comes into focus. Being a transportable and comparatively cheap detection technique, it may be used for speedy on-site detection and characterization of viral variants within the area. Nonetheless, the usefulness of those moveable sequencing instruments is proscribed by the base-calling accuracy points that come up in samples with inadequate nucleic acid focus.

The crew from Ceres Nanosciences, of their latest analysis revealed on the preprint server bioRxiv*, has addressed this limitation through the use of an affinity-based magnetic hydrogel particle enrichment expertise (Nanotrap particle enrichment expertise) that may focus viral particles, resulting in improved detection of many viral brokers together with SARS-CoV-2. With superior base-calling, bioinformatic instruments can confidently distinguish the genetic mutation within the variant from machine error.

What did the researchers do?

The crew developed three workflows to exhibit the robustness and the ease-of-use of Nanotrap particle expertise: a handbook technique with a column-based RNA extraction (Nanotrap Particle Workflow 1), a handbook technique with a magnetic-bead-based RNA extraction (Nanotrap Particle Workflow 2), and an automatic technique with a magnetic-bead-based RNA extraction (Nanotrap Particle Workflow 3).

These workflows had been carried out in SARS-CoV-2 contrived (spiked with 1:10 serial dilutions of heat-inactivated SARS-CoV-2 ranging from 106 TCID50/mL to 102 TCID50/mL) viral transport media (VTM) in addition to remnant diagnostic VTM samples. The Nanotrap particle workflows (+NT) had been in contrast in opposition to the workflows with none Nanotrap particles (-NT).

Extracted RNA was ready for sequencing utilizing the ARTIC nCoV-2019 sequencing protocol and sequenced on the ONT Mk1C sequencing platform, adopted by information evaluation.

Moreover, real-time RT-PCR was carried out on RNA extracted from all three workflows to determine a possible correlation between the 2 assays and ensure the presence of SARS-CoV-2.

Nanotrap particles enhance sequencing outcomes

With Nanotrap Workflow 1, Nanotrap particles considerably improved sequencing outcomes at varied virus concentrations when in comparison with the workflow with out Nanotrap particles. A 6.0X improve in reads mapped to SARS-CoV-2 was noticed at 106 TCID50/mL and a 2.0X improve was seen at 105 TCID50/mL. These enhancements had been statistically important. Viral detection in real-time qPCR was additionally considerably improved by two PCR Cycle thresholds (Ct) throughout the primary 4 serial dilutions.

As column-based RNA extractions are extra acceptable when working with much less variety of samples, the crew tried to evaluate the Nanotrap particles’ potential to enhance on sequencing when utilizing RNA extracted by way of magnetic beads (Nanotrap Workflow 2). Right here, an enchancment of 1.9X in SARS-CoV-2 mapped reads was noticed at 106 TCID50/mL and an enchancment of 1.4X at 105 TCID50/mL. Moreover, real-time qPCR detection of SARS-CoV-2 was enhanced, offering a median 1.5 Ct enchancment at 106-102 TCID50/mL.

“RT-PCR outcomes confirmed Nanotrap particle enrichment was efficacious for decrease focus samples for each workflows, probably suggesting that on an alternate sequencing platform with higher general sensitivity, Nanotrap particles may additionally enhance sequencing of those decrease titer virus samples”, the crew highlights.

To check the efficacy of Nanotrap particles with actual scientific samples, the crew evaluated the Nanotrap particle workflows utilizing 10 diagnostic remnant scientific swab samples with reported qPCR Ct values starting from 24 to 35. The crew quantified each whole viral mapped reads and the related % genome protection at 30x depth of the processed samples.

Nanotrap Particle Workflow 1 resulted in a major 7X enchancment in whole viral reads mapped throughout all 10 diagnostic remnant samples, which additional resulted in a median viral genome protection improve of 52% over samples processed with out Nanotrap particles. RT-PCR confirmed the presence of SARS-CoV-2 with a median enchancment of 4 Ct over no Nanotrap particle samples.

Automated Nanotrap Particle Workflow 3 technique on automated KingFisher Apex System additionally demonstrated improved outcomes, with a median enchancment of 42X in whole viral mapped reads that corresponded to a median 51% improve in viral genome protection relative to (-NT) samples. Once more, qPCR confirmed the presence of SARS-CoV-2 for all 10 samples with a median 3.7 Ct enchancment.

Determine one: Nanotrap Particle Workflow 1 Improves Sequencing of Diagnostic Remnant SARS-CoV-2 Samples. 10 SARS-CoV-2 optimistic diagnostic remnant samples had been processed utilizing Nanotrap Particle Workflow 1 [+NT] or the RNEasy Equipment alone [-NT]. Samples then underwent sequencing on a ONT MinION R.9 movement cell and had been analyzed by Viral Mapped Reads to SARS-CoV-2 (A), Viral Genome Protection at 30x depth (B), or RT-PCR (C). [+NT] had been in comparison with [-NT] by paired t-test as a way to assess significance of elevated viral detection (D),(E). ***p<0.001.

Enhanced detection of different respiratory viruses

To verify the enriching potential of Nanotrap particles for different viruses and never simply SARS-CoV-2, the crew equally examined RNA extraction with workflow 1 on contrived VTM samples spiked with Influenza A (H1N1) virus and RSV. Noticeably, Nanotrap particles had been capable of enhance sequencing outcomes for each viruses. As with SARS-CoV-2, Nanotrap particles elevated viral mapped reads by 4X for each Influenza A and RSV in comparison with the samples processed with out Nanotrap particles. Moreover, Nanotrap particles considerably improved the detection of viral RNA with qPCR. Based mostly on this experiment, the crew means that Nanotrap particles can be utilized to determine and enhance sequencing outcomes of a number of viruses in VTM samples.

Sequencing library preparation protocol entails the usage of varied enzymes that may be negatively impacted by the presence of detrimental organic materials current in the true human-derived diagnostic samples. Pre-processing with Nanotrap particles permits the seize of viral materials whereas lowering host cell particles and different contaminating materials. The crew thus means that workflows with out Nanotrap particles usually tend to be impacted by inhibition.


Because the viral genome protection was vastly elevated and was nearly improved by 80% within the majority of diagnostic samples, the crew means that utilizing Nanotrap particles can enable for the lodging of extra scientific samples in a single run.

The crew highlights the necessity for a easy and speedy workflow as a way to obtain a excessive pattern throughput in a public well being setting and subsequently recommends the automated Nanotrap Workflow 3 for such settings.

It’s value noting that this automated technique would allow the processing of 96 samples in 1 hour, which is considerably sooner and way more consumer pleasant than the manual-column extraction technique, making this a pretty proposition for medium- to high-throughput laboratories”

Moreover, Nanotrap particle workflows can be utilized for the development of broad-scale viral detection by sequencing as demonstrated from the sequencing experiments performed on Influenza A and RSV.

General, the observations counsel that Nanotrap particle enrichment permits for sequencing of decrease titer scientific samples in VTM utilizing the ONT MinION Sequencer, which in any other case could not have been appropriate for sequencing.

A Nanotrap particle concentrating technique paired with a ONT sequencing platform permits for a strong sequencing instrument that might probably be deployed in an space with lack of entry to extra conventional sequencing or pattern processing gear” the crew concludes.

Determine two: Nanotrap Particle Workflow 3 Improves Sequencing Output of Diagnostic Remnant SARS-CoV-2 Samples. 10 SARS-CoV-2 optimistic diagnostic remnant samples had been processed utilizing Nanotrap Particle Workflow 3 [+NT] or the MagMAX package alone [-NT]. Samples then underwent sequencing on a ONT MinION R.9 movement cell and had been analyzed by Viral Mapped Reads to SARS-CoV-2 (A), Viral Genome Protection at 30x depth (B), or RT-PCR (C). [+NT] had been in comparison with [-NT] by paired t-test as a way to assess significance of elevated viral detection (D), (E). * p<0.05, ** p<0.01.

*Necessary discover

bioRxiv publishes preliminary scientific studies that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information scientific observe/health-related habits, or handled as established info.



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