Nucleic Acid Analysis

What We Know About the COVID-19 and the SARS-CoV-2 Virus

Posted on by Jordan Villanueva
David Goodsell image of SARS-2-CoV
Image by David Goodsell

In the nine months since the first cases of COVID-19 were noticed in Wuhan, China, the virus has spread around the globe and infected over 22 million people. As with all emerging infectious diseases, we often find ourselves with more questions than answers. However, through the tireless work of researchers, doctors and public health officials worldwide, we have learned a lot about the virus, how it spreads and how to contain it.

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Using the Power of Technology for Viral Outbreaks

Posted on by Sara Klink
Artist’s rendition of a virus particle.

When the world is experiencing a viral pandemic, scientists and health officials quickly want data-driven answers to understand the situation and better formulate a public health response. Technology provides tools that researchers can use to develop a rapid sequencing protocol. With such a protocol, the data generated can help answer questions about disease epidemiology and understand the interaction between host and virus. Even better: If the protocol is freely available and based on cheap, mobile sequencing systems.

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Emergency Use Authorization: The What, the Why and the How

Posted on by Promega

This blog is written by guest blogger, Heather Tomlinson, former Director of Clinical Diagnostics at Promega.

Finding safe and effective treatments for human diseases takes time.  Medication and diagnostic tests can take decades to discover, develop and prove safe and effective.  In the United States, the FDA stands as the gold-standard gatekeeper to ensure that treatments and tests are reliable and safe. The time we wait in review and clearance means less risk of ineffective or unsafe treatments.

And yet, in a pandemic, we are behind before we even start the race to develop diagnostic tests, so critical for understanding how an infectious disease is spreading. That is when processes like the FDA’s fast track of Emergency Use Authorization (EUA) are critical. Such authorization allows scientists and clinicians to be nimble and provide the best possible test protocol as quickly as possible, with the understanding that these protocols will continue to be evaluated and improved as new information becomes available. The EUA focuses resources and accelerates reviews that keep science at the fore and gets us our best chance at staying safe and healing.

The Maxwell 48 RSC Instrument and the Maxwell RSC Total Viral Nucleic Acid Isolation Kit are now listed as options within the CDC EUA protocol.

For scientists working around the clock, the FDA’s EUA process is ready to review and respond. Getting an EUA  gives clinical labs a very specific and tested resource to guide them to the tools and tests to use in a crisis.

Typically the Centers for Disease Control (CDC) will develop the first test or protocol that receives FDA EUA in response to a crisis like a pandemic.  For COVID-19 the CDC 2019-Novel Coronavirus Real-Time RT-PCR Diagnostic Panel received FDA EUA clearance in early February. This is the test protocol used by the public health labs that work with the CDC and test manufacturers around the world.

Throughout a crisis such as the current pandemic, scientists continually work to improve the testing protocols and add options to the EUA protocols. This enables more flexibility in the test protocols. Promega is fortunate to play a part of the CDC EUA equation for diagnostic testing. Our GoTaq® Probe 1-Step PRT-qPCR System is one of a few approved options for master mixes in the  CDC qPCR diagnostic test,  and now our medium-throughput Maxwell 48 Instrument and Maxwell Viral Total Nucleic Acid Purification Kit  were added to the CDC protocol as an option for the RNA isolation step as well. These additions to the CDC EUA means that laboratories have more resources at their disposal for the diagnostic testing which is so critical to effective pandemic response.

The Emergency Use Authorization provides the FDA guidance to strengthen our nation’s public health during emergencies, such as the current COVID-19 pandemic. The EUA allows continual improvement of an authorized protocol through the collaborative efforts scientists in all academia, government and industry to identify and qualify the most reliable technologies and systems, giving labs more flexibility as new products are added as options.

Dr. Tomlinson was the Director for the Global Clinical Diagnostics Strategic Business Unit at Promega Corporation bringing over 15 years of experience in clinical diagnostic test development. She was responsible for leading the team that drives strategy in the clinical market for Promega. Her background was in infectious disease diagnostic testing, with a focus on HIV drug resistance and evolution. Her last work focused on oncology companion diagnostic test development.  Heather was an accomplished international presenter, delivering conference presentations in the United States, Europe, Asia, and Africa. Heather passed away in 2023.

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Small Changes With Large Consequences: The Role of Genetic Variance in Disease Development

Posted on by Sara Klink
Structure of Human Ferrochelatase
Human Ferrochelatase 2 angstrom crystal structure. Generated from 1HRK (RCSB PDB) using Pymol. Copyright: Sarah Wilson / CC BY-SA

Understanding how disease states arise from genetic variants is important for understanding disease resistance and progression. What can complicate our understanding of disease development is when two people have the same genetic variant, but only one has the disease. To investigate what might be happening with ferrochelatase (FECH) variant alleles that result in erythropoietic protoporphyria (EPP), scientists used next-generation sequencing (NGS) along with RNA analysis and DNA methylation testing to assess the FECH locus in 72 individuals from 24 unrelated families with EPP.

What is FECH and its relationship to EPP?

FECH is the gene for ferrochelatase, the last enzyme in the pathway that synthesizes heme. The inherited metabolic disorder, EPP, is caused when the activity of FECH is reduced to less than a third of normal levels thus, increasing the levels of protoporphyrin (PPIX) without metal in erythrocytes. The consequences of the low-metal PPIX include severe phototoxic skin reactions and hepatic injury due to PPIX accumulation in the liver.

How does FECH expression affect EPP?

The EPP disease state is not simply the lack of two functional FECH genes. Disease occurs with a hypomorphic allele, mutations in FECH that reduce its function, in trans to a null FECH allele. Researchers focused on three common variants called the GTC haplotype that are associated with expression quantitative trait loci (eQTL) that reduce FECH activity. Interestingly, these three variants have been found in trans, but researchers wanted to learn if there were individuals who were homozygous for the GTC allele and how EPP manifested for them.

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Go fISH! Using in situ Hybridization to Search for Expression of a SARS-CoV-2 Viral Entry Protein

Posted on by Leah Cronan

Loss of smell (olfaction) is a commonly reported symptom of COVID-19 infection. Recently, Bilinska, et al. set out to better understand the underlying mechanisms for loss of smell resulting from SARS-CoV-2 infection. In their research, they used in situ hybridization to investigate the expression of TMPRSS2, a SARS-CoV-2 viral entry protein in olfactory epithelium tissues of mice.

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In Vitro Transcription and the Use of Modified Nucleotides

Posted on by Leah Cronan
In vitro transcription
RNA polymerase unwinds DNA strands for transcription.

Transcription is the production of RNA from a DNA sequence. It’s a necessary life process in most cells. Transcription performed in vitro is also a valuable technique for research applications—from gene expression studies to the development of RNA virus vaccines.

During transcription, the DNA sequence is read by RNA polymerase to produce a complimentary, antiparallel RNA strand. This RNA strand is called a primary transcript, often referred to as an RNA transcript. In vitro transcription is a convenient method for generating RNA in a controlled environment outside of a cell.

In vitro transcription offers flexibility when choosing a DNA template, with a few requirements. The template must be purified, linear, and include a double stranded promoter region. Acceptable template types are plasmids or cloning vectors, PCR products, synthetic oligos (oligonucleotides), and cDNA (complimentary DNA). 

In vitro transcription is used for production of large amounts of RNA transcripts for use in many applications including gene expression studies, RNA interference studies (RNAi), generation of guide RNA (gRNA) for use in CRISPR, creation of RNA standards for quantification of results in reverse-transcription quantitative PCR (RT-qPCR), studies of RNA structure and function, labeling of RNA probes for blotting and hybridization or for RNA:protein interaction studies, and preparation of specific cDNA libraries, just to name a few!

In vitro transcription can also be applied in general virology to study the effects of an RNA virus on a cell or an organism, and in development and production of RNA therapeutics and RNA virus vaccines. The large quantity of viral RNA produced through in vitro transcription can be used as inoculation material for viral infection studies. Viral mRNA transcripts, typically coding for a disease-specific antigen, can be quickly created through in vitro transcription, and used in the production of vaccines and therapeutics.

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Using molecular biology and biochemistry to detect blood doping

Posted on by Michele Arduengo

Monitoring the use of performance-enhancing substances among athletes is complex and the requirements for tests and assays that detect use of such substances have changed significantly over the last few decades.

The haematological (blood) module of Athlete Biological Passport was adopted December 1, 2009 (ABP) by the World Anti-Doping Agency. The module sets out standard protocols to monitor doping of professional athletes by looking at changes in biological parameters, without relying on the detection of illegal compounds in body fluids. Such biological methods eliminate the need to develop and validate a test to detect every new compound that can be used for doping. The current version of the ABP, adopted in 2014, also adds monitoring of certain steroid use indicators from urine samples.

Blood doping which aims at increasing red blood cells so that more oxygen can be transported to muscles to increase stamina or performance is particularly difficult to detect. There are typically three ways that it is accomplished: use of erythropoietin (EPO) or synthetic oxygen carriers and blood transfusions. While transfusions of large volumes of blood or use of EPO can be detected, microdosing EPO or transfusing smaller volumes of packed red blood cells is much harder to detect.

Nicolas Leuenberger and colleagues at the Swiss Laboratory for Doping Analysis have developed a method to detect blood doping. In addition to addressing the detection of blood doping, his laboratory is also concerned about easing the transport and storage requirements for samples and ensuring that sample collection does not adversely affect athlete performance.

Improving Collection and Storage of Blood Samples

Because sample collection and storage are so critical to accurate test results, any new assays developed to detect blood doping benefit from ease of collection and storage. The Leuenberger laboratory investigated the use of the TAP™ Push Button collection device, which is billed as a simple method for blood collection that is easy to use and eliminates the need for painful needle sticks or finger pricks that can affect athlete performance. After TAP collection, 20µl of blood from the device was placed on to filter paper and dried (dried blood samples; DBS), which are much easier to store and transport from collection site to laboratory.

An RNA Biomarker for Blood Doping

Blood withdrawal and autologous transfusion or recombinant human EPO injection stimulate erythropoiesis and immature red blood cells can be distinguished based on their gene expression profiles. One of the genes that is expressed by immature red blood cells is aminoleuvulinate synthase 2, a gene that encodes an enzyme ALAS2 involved in the synthesis of heme, a pathway active during RBC maturation. RNA transcripts are unstable and tend to degrade rapidly, so isolating linear RNA transcripts from a collected sample can be difficult. However circular RNAs (circRNAs) are a class of RNA molecule produced by the backsplicing of pre-mRNAs that are high in abundance, quite stable and maintain cell-type specific expression. The Leuenberger laboratory developed a method for measuring the linear and circular forms of ALAS2 RNA in DBS to monitor erythropoiesis.

One of the greatest challenges in developing this protocol was achieving efficient RNA extraction from only 20ul of dried blood. Leuenberger and his colleagues adopted a two-step purification; beginning with a phenol:chloroform extraction on the DBS followed by a further purification on the Maxwell® RSC automated instrument, using the Maxwell RSC miRNA Serum and Plasma kit. Switching from a manual to an automated method for the second step was crucial. It reduced chances of contamination as well reduced pipetting errors, without compromising good quality and yield of RNA therefore contributing to assay reproducibility. To normalize volumes within the blood spot, the protocol uses RNA produced by housekeeping genes. The work to automate the assay has been published in Bioanalysis.

What’s Next

This protocol is being tested to see if microdosing of EPO or small transfusions can also be detected by monitoring ALAS2 RNA expression in DBS. The Swiss laboratory of Doping Analysis is also in the process of developing a method to detect gene doping by isolating plasmid DNA from whole blood samples, using the Maxwell® RSC.

Additionally, the collection and storage methods used have implications for the clinic, especially for patients that need routine blood monitoring. The ability to isolate circular RNAs shows promise in forensic applications to identify body fluids. 

Want to know more about how the Maxwell® RSC can give you the freedom to focus on the work that interests you the most? To learn more, click here.

Promega Leverages Long-Time Experience in MSI Detection with European Launch of CE-Marked IVD Assay for Microsatellite Instability

Posted on by Kelly Grooms

The genetic abnormality called microsatellite instability, or MSI, has been linked to cancer since its discovery in 1993 (1). MSI is the accumulation of insertion or deletion errors at microsatellite repeat sequences in cancer cells and results from a functional deficiency within one or more major DNA mismatch repair proteins (dMMR).  This deficiency, and the resulting genetic instability, is closely related to the carcinogenicity of tumors (2).

Historically MSI has been used to screen for Lynch Syndrome, a dominant hereditary cancer propensity. More recently, tumors with deficient MMR function have been identified as being more likely to respond to immune checkpoint inhibitor (ICI) therapies (3.). Because MSI can be the first evidence of an MMR deficiency, MSI-High status is predictive of a positive response to immunotherapies such as ICI therapies. (3).

Learn more about MSI in this short animation.
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38 Years After First Release, RNasin Protects COVID-19 Tests

Posted on by Jordan Villanueva

A protein first purified and sold by Promega almost four decades ago has emerged as a crucial tool in many COVID-19 testing workflows. RNasin® Ribonuclease Inhibitor was first released in 1982, only four years after the company was started. At that time, the entire Promega catalog fit on a single sheet of 8.5 × 11” paper, and RNasin was one of the first products to draw widespread attention to Promega. Today, the demand for this foundational product has skyrocketed as it supports labs responding to the COVID-19 pandemic.

What is RNasin® Ribonuclease Inhibitor?

RNA is notoriously vulnerable to contamination by RNases. These enzymes degrade RNA by breaking the phosphodiester bonds forming the backbone of the molecule. To say that RNases are everywhere is barely an exaggeration – almost every known organism produces some form of RNase, and they’re commonly found in all kinds of biological samples. They’re easily introduced into experimental systems, since even human skin secretes a form of RNase. Once they’re present, it’s very hard to get rid of them. Even an autoclave can’t inactivate RNases; the enzymes will refold and retain much of their original activity.

RNasin® Ribonuclease Inhibitor is a protein that has been shown to inhibit many common contaminating RNases, but without disrupting the activity of enzymes like reverse transcriptase that may be essential to an experiment. It works by binding to the RNase enzyme, prevent it from acting on RNA molecules. This is important for ensuring that RNA samples are intact before performing a complex assay.

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RT-qPCR and qPCR Assays—Detecting Viruses and Beyond

Posted on by Kelly Grooms

We have all been hearing a lot about RT-PCR, rRT-PCR and RT-qPCR lately, and for good reason. Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) is the technique used in by the Center for Disease Control (CDC) to test for COVID-19. Real-time RT-PCR, or quantitative RT-PCR (RT-qPCR)*, is a specialized PCR technique that visualizes the amplification of the target sequence as it happens (in real-time) and allows you to measure the amount of starting target material in your reaction. You can read more about the basics of this technique, and watch a webinar here. For more about RT-PCR for COVID-19 testing, read this blog.

Both qPCR and RT-qPCR are powerful tools for scientists to have at their disposal. These fundamental techniques are used to study biological processes in a wide range of areas. Over the decades, Promega has supported researchers with RT-qPCR and qPCR reagents and systems to study everything from diseases like COVID-19 and cancer to viruses in elephants and the circadian rhythm of krill.  

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