Though they are a mystery, once solved, Obelisks could lead to new biomarkers for clinical laboratory testing
Microbiologists and clinical laboratories know that human microbiota play many important roles in the body. Now, scientists from Stanford University have discovered an entirely new class of “viroid-like” lifeforms residing inside the human body. The researchers detected their presence in both the gut microbiome and saliva samples. Most interesting of all, the researchers are not sure what the lifeforms actually are.
The Stanford researchers, led by PhD student Ivan Zheludev, called the new discovery “Obelisks” due to their RNA structures, which are short and can fold into structures that resemble rods.
The scientists believe the Obelisks went undetected until now in the human microbiome due to their compact genetic elements, which are only around 1,000 characters or nucleotides in size. A typical human DNA structure consists of around three billion nucleotides.
In an article they published on the biology preprint server bioRxiv titled, “Viroid-like Colonists of Human Microbiomes,” the Stanford researchers wrote, “Here, we describe the ‘Obelisks,’ a previously unrecognized class of viroid-like elements that we first identified in human gut metatranscriptomic data. … Obelisks comprise a class of diverse RNAs that have colonized and gone unnoticed in human and global microbiomes.”
The researchers discovered that Obelisks “form their own distinct phylogenetic group with no detectable sequence or structural similarity to known biological agents.”
This is yet another example of how researchers are digging deeper into human biology and finding things never before identified or isolated.
“I am really impressed by the approach. The authors were really creative,” computational biologist Simon Roux, PhD (above) of the Department of Energy (DEO) Joint Genome Institute at Lawrence Berkeley National Laboratory told Science in response to the Stanford researcher’s published findings. “I think this [work] is one more clear indication that we are still exploring the frontiers of this viral universe. This is one of the most exciting parts of being in this field right now. We can see the picture of the long-term evolution of viruses on Earth start to slowly emerge.” How these findings might eventually spark new biomarkers for clinical laboratory testing remains to be seen. (Photo copyright: Berkeley Lab.)
Researchers Bewildered by Obelisks
In their study, “Zheludev and team searched 5.4 million datasets of published genetic sequences and identified almost 30,000 different Obelisks. They appeared in about 10% of the human microbiomes the team examined,” Science reported.
The Stanford researchers found that various types of Obelisks seem to inhabit different areas of the body. In one dataset, the Obelisks were found in half of the oral samples.
The function of Obelisks is unknown, but their discovery is bewildering experts.
Rod-like secondary structures encompassing the entire genome, and
Open reading frames coding for a novel protein superfamily, which the researchers dubbed “Oblins.”
At least half of the genetic material of the Obelisks was taken up by these Oblins. The researchers suspect those proteins may be involved in the replication process of the newly-discovered lifeforms.
The Oblins are also significantly larger than other genetic molecules that live inside cells and they do not have the genes to create protein shells that RNA viruses live within when they are outside of cells.
“Obelisks, therefore, need some kind of host. The researchers managed to identify one: A bacterium called Streptococcus sanguinis that lives mostly in dental plaque in our mouths. Exactly which other hosts obelisks inhabit is yet another mystery, as are what they do to their host and how they spread,” Vice reported.
“While we don’t know the ‘hosts’ of other Obelisks, it is reasonable to assume that at least a fraction may be present in bacteria,” the researchers noted in their bioRxiv paper.
Researchers are Stumped
The Stanford scientists were unable to identify any impact the Obelisks were having on their bacterial hosts—either negative or positive—or determine how they could spread between cells.
“These elements might not even be ‘viral’ in nature and might more closely resemble ‘RNA plasmids,’” they concluded in their paper.
The Stanford scientists are uncertain as to where or what the hosts of the Obelisks are, but they suspect that at least some of them are present in bacteria. However, Obelisks do not appear to be similar to any biological agents that could provide a link between genetic molecules and viruses.
And so, Obelisks are a true mystery—one the Stanford researchers may one day solve. If they do, new biomarkers for clinical laboratory testing may not be far behind.
The antibodies target portions of the SARS-CoV-2 spike protein that resist mutation, potentially leading to better treatments and vaccines
One challenge in the battle against COVID-19 is the emergence of SARS-CoV-2 variants, especially the Delta variant, which may be more resistant to neutralizing antibodies compared with the original coronavirus. But now, scientists led by researchers at the Fred Hutchinson Cancer Research Center (Fred Hutch) in Seattle say they have identified antibodies that could be broadly protective against multiple sarbecoviruses, the subgenus that contains SARS-CoV-2 as well as SARS-CoV-1, the virus responsible for the 2002-2004 severe acute respiratory syndrome (SARS) outbreak.
In “SARS-CoV-2 RBD Antibodies That Maximize Breadth and Resistance to Escape,” the researchers described how they compared 12 antibodies obtained from patients infected with either SARS-CoV-2 or SARS-CoV-1. They pointed to one antibody in particular—S2H97—that could lead to development of new vaccines and therapies against current and future variants. It might even protect against sarbecoviruses that have not yet been identified, they wrote.
Unsaid in the news release about these research findings is the fact that these particular antibodies could eventually become useful biomarkers for clinical laboratory tests designed to help physicians determine which patients have these antibodies—and the protection from infection they represent—and which do not.
So far, however, S2H97 has only been tested in hamsters. But results are promising.
“This antibody, which binds to a previously unknown site on the coronavirus spike protein, appears to neutralize all known sarbecoviruses—the genus of coronaviruses that cause respiratory infections in mammals,” said Jay Nix, PhD, an affiliate in Berkeley Lab’s Biosciences Area and Beamline Director of the Molecular Biology Consortium at Berkeley Lab’s Advanced Light Source (ALS), in a Berkeley Lab news release. “And, due to the unique binding site on mutation-resistant part of the virus, it may well be more difficult for a new strain to escape,” he added.
Scientists have long known that the SARS-CoV-2 virus uses the spike protein to attach to human cells. The federal Centers for Disease Control and Prevention (CDC) notes that the variants have mutations in their spike proteins that make some of them more transmissible.
The Delta variant, the CDC notes, was the predominant variant in the US as of August 28, 2021. It “has been shown to have increased transmissibility, potential reduction in neutralization by some monoclonal antibody treatments, and reduction in neutralization by post-vaccination sera,” the agency states.
The key to S2H97, the researchers wrote, is that it targets a portion of the spike protein that is common among sarbecoviruses, and that is likely to be resistant to mutations.
The researchers used a variety of techniques to analyze how the 12 antibodies bind to the virus. They “compiled a list of thousands of mutations in the binding domains of multiple SARS-CoV-2 variants,” Nature reported. “They also catalogued mutations in the binding domain on dozens of SARS-CoV-2-like coronaviruses that belong to a group called the sarbecoviruses. Finally, they assessed how all these mutations affect the 12 antibodies’ ability to stick to the binding domain.”
William Schaffner, MD (above), Professor of Preventive Medicine in the Department of Health Policy as well as Professor of Medicine in the Division of Infectious Diseases at the Vanderbilt University School of Medicine in Nashville, believes that “people who test positive for SARS-CoV-2 and who are at risk of progressing to severe disease—including those who are over the age of 65 years and those who have weakened immune systems—should talk with a doctor about receiving monoclonal antibody treatment,” Medical News Today reported. “[The monoclonal antibody treatment is] designed to prevent the evolution of the infection from a mild infection into a serious one,” he noted. “In other words, you’ve just [contracted the virus], but we can now give you a medication that will help prevent [you] being hospitalized and getting seriously ill.” (Photo copyright: Vanderbilt University.)
Earlier Antibody Treatment Receives an EUA from the FDA
In issuing the EUA for sotrovimab, the FDA cited “an interim analysis from a phase 1/2/3 randomized, double-blind, placebo-controlled clinical trial in 583 non-hospitalized adults with mild-to-moderate COVID-19 symptoms and a positive SARS-CoV-2 test result. Of these patients, 291 received sotrovimab and 292 received a placebo within five days of onset of COVID-19 symptoms.”
Among these patients, 21 in the placebo group were hospitalized or died compared with three who received the therapy, an 85% reduction.
“While preventive measures, including vaccines, can reduce the total number of cases, sotrovimab is an important treatment option for those who become ill with COVID-19 and are at high risk—allowing them to avoid hospitalization or worse,” stated Adrienne E. Shapiro, MD, PhD, of the Fred Hutchinson Cancer Research Center in a GSK news release. Shapiro was an investigator in the clinical trial.
The EUA allows use of sotrovimab in patients who have tested positive for SARS-CoV-2, have mild-to-moderate symptoms, and “who are at high risk for progression to severe COVID-19, including hospitalization or death. This includes, for example, individuals who are 65 years of age and older or individuals who have certain medical conditions.” It is not authorized for patients who are hospitalized or for those who require oxygen therapy.
The therapy was originally known as VIR-7831. The companies say they have developed a similar treatment, VIR-7832, with modifications designed to enhance T cell function against the disease.
The antibody, they wrote, targets a region of the SARS-CoV-1 spike protein that is “highly conserved” among sarbecoviruses. Clinical laboratory testing, they wrote, also indicated that the therapy was likely to be effective against known SARS-CoV-2 variants.
“Our distinctive scientific approach has led to a single monoclonal antibody that, based on an interim analysis, resulted in an 85% reduction in all-cause hospitalizations or death, and has demonstrated, in vitro, that it retains activity against all known variants of concern, including the emerging variant from India,” stated Vir Biotechnology CEO George Scangos, PhD, in the GSK news release. “I believe that sotrovimab is a critical new treatment option in the fight against the current pandemic and potentially for future coronavirus outbreaks, as well.”
Pathologists and clinical laboratory managers working with rapid molecular tests and antibody tests for COVID-19 will want to monitor the development of monoclonal antibody treatments, as well as further research studies that focus on these specific antibodies.
With 100% of the human genome mapped, new genetic diagnostic and disease screening tests may soon be available for clinical laboratories and pathology groups
Utilizing technology developed by two different biotechnology/genetic sequencing companies, an international consortium of genetic scientists claim to have sequenced 100% of the entire human genome, “including the missing parts,” STAT reported. This will give clinical laboratories access to the complete 3.055 billion base pair (bp) sequence of the human genome.
If validated, this achievement could greatly impact future genetic research and genetic diagnostics development. That also will be true for precision medicine and disease-screening testing.
Completing the First “End-to-End” Genetic Sequencing
In June of 2000, the Human Genome Project (HGP) announced it had successfully created the first “working draft” of the human genome. But according to the National Human Genome Research Institute (NHGRI), the draft did not include 100% of the human genome. It “consists of overlapping fragments covering 97% of the human genome, of which sequence has already been assembled for approximately 85% of the genome,” an NHGRI press release noted.
“The original genome papers were carefully worded because they did not sequence every DNA molecule from one end to the other,” Ewan Birney, PhD, Deputy Director General of the European Molecular Biology Laboratory (EMBL) and Director of EMBL’s European Bioinformatics Institute (EMBL-EBI), told STAT. “What this group has done is show that they can do it end-to-end. That’s important for future research because it shows what is possible,” he added.
In their published paper, the T2T scientists wrote, “Addressing this remaining 8% of the genome, the Telomere-to-Telomere (T2T) Consortium has finished the first truly complete 3.055 billion base pair (bp) sequence of a human genome, representing the largest improvement to the human reference genome since its initial release.”
Tale of Two Genetic Sequencing Technologies
Humans have a total of 46 chromosomes in 23 pairs that represent tens of thousands of individual genes. Each individual gene consists of numbers of base pairs and there are billions of these base pairs within the human genome. In 2000, scientists estimated that humans have only 30,000 to 35,000 genes, but that number has since been reduced to just above 20,000 genes.
According to STAT, “The work was possible because the Oxford Nanopore and PacBio technologies do not cut the DNA up into tiny puzzle pieces.”
PacBio used HiFi sequencing, which is only a few years old and provides the benefits of both short and long reads. STAT noted that PacBio’s technology “uses lasers to examine the same sequence of DNA again and again, creating a readout that can be highly accurate.” According to the company’s website, “HiFi reads are produced by calling consensus from subreads generated by multiple passes of the enzyme around a circularized template. This results in a HiFi read that is both long and accurate.”
Oxford Nanopore uses electrical current in its sequencing devices. In this technology, strands of base pairs are pressed through a microscopic nanopore one molecule at a time. Those molecules are then zapped with electrical currents to enable scientists to determine what type of molecule they are and, in turn, identify the full strand.
The T2T Consortium acknowledge in their paper that they had trouble with approximately 0.3% of the genome, but that, though there may be a few errors, there are no gaps.
“You’re just trying to dig into this final unknown of the human genome,” Karen Miga (above), Assistant Professor in the Biomolecular Engineering Department at the University of California, Santa Cruz (UCSC), Associate Director at the UCSC Genomics Institute, and lead author of the T2T Consortium study, told STAT. “It’s just never been done before and the reason it hasn’t been done before is because it’s hard.” (Photo copyright: University of California, Santa Cruz.)
Might New Precision Medicine Therapies Come from T2T Consortium’s Research?
The researchers claim in their paper that the number of known base pairs has grown from 2.92 billion to 3.05 billion and that the number of known genes has increased by 0.4%. Through their research, they also discovered 115 new genes that code for proteins.
The T2T Consortium scientists also noted that the genome they sequenced for their research did not come from a person but rather from a hydatidiform mole, a rare growth that occasionally forms on the inside of a women’s uterus. The hydatidiform occurs when a sperm fertilizes an egg that has no nucleus. As a result, the cells examined for the T2T study contained only 23 chromosomes instead of the full 46 found in most humans.
Although the T2T Consortium’s work is a huge leap forward in the study of the human genome, more research is needed. The consortium plans to publish its findings in a peer-reviewed medical journal. In addition, both PacBio and Oxford Nanopore plan to develop a way to sequence the entire 46 chromosome human genome in the future.
The future of genetic research and gene sequencing is to create technologies that will allow researchers to identify single nucleotide polymorphisms (SNPs) that contain longer strings of DNA. Because these SNPs in the human genome correlate with medical conditions and response to specific genetic therapies, advancing knowledge of the genome can ultimately provide beneficial insights that may lead to new genetic tests for medical diagnoses and help medical professionals determine the best, personalized therapies for individual patients.
Researchers found evidence indicating that the virus has—under selection pressure—made itself more stable, giving it a “significant boost in infectivity”
While the COVID-19 pandemic continues to spread across the United States and throughout the world, new research suggests that a coming genetic mutation within the SARS-CoV-2 coronavirus may make it much more dangerous than it already is. This finding has significant implications for clinical laboratories that perform COVID-19 testing and the in vitro diagnostics (IVD) companies that develop and manufacture tests for COVID-19.
The mutation, called D614G, will provide the coronavirus with sturdier spikes that will increase its ability to latch onto and infect cells. That’s according to a study conducted at The Scripps Research Institute (Scripps) in Jupiter, Fla., which found that a mutated coronavirus may be up to 10 times more infectious than the original strain.
“Viruses with this mutation were much more infectious than those without the mutation in the cell culture system we used,” said Hyeryun Choe, PhD, Professor, Department of Immunology and Microbiology, Scripps Research, and senior author of the study, in a Scripps news release.
A More Flexible and Potent Coronavirus May Be Coming
The researchers found that coronavirus particles containing the mutation tend to have four to five times more functional spikes than particles without the mutation. The spikes enable the virus to bind to cells more easily. The research suggests that the greater the number of functional spikes on the viral surface the greater the flexibility and potency of the coronavirus.
In the Scripps news release, Farzan said, “more flexible spikes allow newly made viral particles to navigate the journey from producer cell to target cell fully intact, with less tendency to fall apart prematurely.
“Over time, it has figured out how to hold on better and not fall apart until it needs to,” he added. “The virus has, under selection pressure, made itself more stable.”
The image above, taken from the Scripps Research news release, shows “a cryogenic electron microscope image of a SARS-CoV-2 spike protein side view, the S1 section of the spike is shown in green and the S2 portion is shown in purple. This unique two-piece system has shown itself to be relatively unstable. A new mutation has appeared in the viral variant most common in New York and Italy that makes this spike both more stable and better able to infect cells.” (Graphic and caption copyright: Andrew Ward lab, Scripps Research.)
Mutation Makes SARS-CoV-2 Coronavirus ‘Much More Stable’
The two Scripps scientists have studied coronaviruses for nearly 20 years and performed extensive research on the Severe Acute Respiratory Syndrome (SARS) outbreak that occurred in 2003. They noted that there is a difference between spike proteins of SARS, an earlier strain of coronavirus, and the new SARS-CoV-2 strain.
The protein spikes of both strains were originally tripod shaped. However, the spikes of the SARS-CoV-2 coronavirus are divided into two different segments: S1 and S2. According to the published study: “The S1domain mediates receptor binding, and the S2 mediates downstream membrane fusion.”
This feature originally produced unstable spikes, but with the D614G mutation, the tripod breaks less frequently, which makes more of the spikes fully functional and the virus more infectious.
“Our data are very clear, the virus becomes much more stable with the mutation,” Choe said in the news release.
Is COVID-19 Spread Due to ‘Founder Effect’
The scientists also examined whether the spread of COVID-19 could have been the result of the “Founder Effect,” which is seen when a small number of variants fan out into a wide population by chance. Could the founder effect explain why COVID-19 outbreaks in some areas of the world were more severe than others? The researchers believe their data definitively answered that question.
“There have been at least a dozen scientific papers talking about the predominance of this mutation,” Farzan said. “Are we just seeing a founder effect? Our data nails it. It is not the founder effect.”
Hyeryun Choe, PhD (left), and Michael Farzan, PhD (right), scientists at Scripps Research explained that their research was performed using engineered viruses and that their observations of the virus and its mutation may not translate to increased transmissibility when a virus attaches to a host outside the lab. COVID-19 and its mutation appear to be relatively stable and are mutating at a rate slower than that of the seasonal flu, which may be critical factors in the development of a vaccine. (Photos copyright: Scripps Research.)
Findings Raise ‘Interesting’ Questions about the COVID-19 Coronavirus
Nevertheless, the two scientists are curious about some of their findings. “Our data raise interesting questions about the natural history of SARS-CoV-2 as it moved presumably from horseshoe bats to humans. At some point in this process, the virus acquired a furin-cleavage site, allowing its S1/S2 boundary to be cleaved in virus-producing cells. In contrast, the S1/S2 boundary of SARS-CoV-1, and indeed all SARS-like viruses isolated from bats, lack this polybasic site and are cleaved by TMPRSS2 or endosomalcathepsins in the target cells.
“In summary, we show that an S protein mutation that results in more transmissible SARS-CoV-2 also limits shedding of the S1 domain and increases S-protein incorporation into the virion. Further studies will be necessary to determine the impact of this change on the nature and severity of COVID-19,” the Scripps researchers concluded.
However, not all Scripps researchers agreed with the conclusions of Choe and Farzan’s research.
The Times of Israel reported that Kristian Andersen, PhD, a professor in the Department of Immunology and Microbiology, Scripps California Campus, told the New York Times that “other analyses of virus variants in labs had not found significant differences in infection rates.”
“That’s the main reason that I’m so hesitant at the moment,” Andersen said. “Because if one really was able to spread significantly better than the other, then we would expect to see a difference here, and we don’t.”
Times of Israel also reported that “In late May researchers in University College London said their studies of the genomes of more than 15,000 samples had not shown one strain being more infectious than others.”
So, the jury’s out. Nonetheless, clinical laboratory leaders will want to remain vigilant. A sudden increase in COVID-19 infection rates will put severe strain on already strained laboratory supply chains.
