What animal can be found around the globe that outnumbers humans three to one? Gallus gallus domesticus, the humble chicken. The human appetite for eggs and lean meat drive demand for this feathered bird, resulting in a poultry population of over 20 billion.
Controversy over the origin of the domestic chicken (when, where and which species) have lead some researchers to look for that information in the genomes of contemporary chicken breeds and wild jungle fowl, the candidates from which chickens were derived. By sequencing over 600 genomes from Asian domestic poultry as well as 160 genomes from all four wild jungle fowl species and the five red jungle fowl subspecies, Wang et al. wanted to understand and identify the relationships and relatedness among these species and derive where domesticated chickens first arose.
As the SARS‐CoV‐2 pandemic continues to rage across the United States and around the globe, the demand for COVID‐19 testing is increasing. The vast majority of the COVID-19 assays use RT‐qPCR to detect the viral RNA in patient samples such as nasopharyngeal swabs, which are collected and stored in viral or universal transport media (VTM/UTM). The general workflow for these COVID‐19 assays can be broken down as follows:
Collect and store patient samples
Ship samples to testing laboratory
Extract RNA from samples
Amplify and analyze samples
While many companies who manufacture the products that are used in these steps have been able to adapt and significantly increase their production capacities, there are still gaps between the supply of these products and the global test demand. Both the sample collection and storage step and the RNA extraction/purification step have a tendency to bottleneck and experience supply constraints. One way to address these bottlenecks and expand production capacity for these in‐demand products is to evaluate the viability of skipping a step in the workflow, without hindering the ability to detect viral RNA from samples.
Lynch Syndrome is the autosomal dominant hereditary predisposition to develop colorectal cancer and certain other cancers. This simple, one sentence definition seems woefully inadequate considering the human toll this condition has inflicted on the families that have it in their genetic pedigree.
They Called it a Curse
To one family, perhaps the family when it comes to this condition, Lynch Syndrome has meant heartache and hope; grief and joy; death and life. Their story is told by Ami McKay in her book Daughter of Family G, and it is at once both a memoir of a Lynch Syndrome previvor (someone with a Lynch Syndrome genomic mutation who has not yet developed cancer) and a poignant and honest account of the family that helped science put name to a curse.
“The doctors called it cancer. I say it’s a curse. I wish I knew what we did to deserve it.”
Anna Haab from Daughter of Family G (1)
The scientific community first met “Family G” as the meticulously created family tree, filled with the stunted branches that mark early deaths by cancer. The pedigree was first published in 1913 in Archives of Internal Medicine (2). In the article, Dr. Alderd Warthin wrote: “A marked susceptibility to carcinoma exists in the case of certain family generations and family groups.” In 1925, an expanded pedigree of circles and squares was published in Dr. Warthin’s follow up study in the Journal of Cancer Research (3). But each circle and square in that pedigree denotes a person. Each line represents their dreams together for the future, and Ms. McKay wants us to know their names: Johannes and Anna, Kathrina, Elmer, Tillie, Sarah Anne (Sally); and—most importantly—Pauline. Because without Pauline there would be no story.
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.
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.
This blog is written by guest blogger, Heather Tomlinson, 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.
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 have been 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 is the Director for the Global Clinical Diagnostics Strategic Business Unit at Promega Corporation with over 15 years of experience in clinical diagnostic test development. She is responsible for leading the team that drives strategy in the clinical market for Promega. Her background is in infectious disease diagnostic testing, with a focus on HIV drug resistance and evolution. Her recent work has been in oncology companion diagnostic test development. Heather has is an accomplished international presenter, delivering conference presentations in the United States, Europe, Asia, and Africa.
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.
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.
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.