Viral reservoir could be behind persistence, says study, which also suggests a blood biomarker could be found for clinical laboratory testing
Microbiologists and virologists working closely with physicians treating long COVID-19 patients will gain new insights in a study that found coronavirus spike protein in COVID-19 patients’ blood up to 12 months after diagnosis. The researchers believe their findings could be used to develop a clinical laboratory biomarker for long COVID-19.
Researchers at Brigham and Women’s Hospital and Massachusetts General Hospital said medical experts are not sure why some people have unwelcome symptoms weeks and months after a positive COVID-19 diagnosis, while others clear the infection without lingering effects.
The scientists believe if this work is validated, clinical laboratories might gain an assay to use in the diagnosis of long COVID-19.
“The half-life of spike protein in the body is pretty short, so its presence indicates that there must be some kind of active viral reservoir,” said David Walt, PhD (above), Professor of Pathology, Brigham and Women’s Hospital, and lead author of the study that found coronavirus spike protein in long COVID patients. The study findings indicate a potential clinical laboratory biomarker for long COVID-19. (Photo copyright: Brigham and Women’s Hospital.)
Viral Reservoir Possibly Behind Long COVID-19
The study suggests that SARS-CoV-2 finds a home in the body, particularly the gastrointestinal tract, “through viral reservoirs, where it continues to release spike protein and trigger inflammation,” Medical News Today reported.
Lead author of the study David Walt, PhD, Professor of Pathology, Brigham and Women’s Hospital and the Hansjörg Wyss Professor Biologically Inspired Engineering at Harvard Medical School, told The Guardian he “was motivated to carry out the study after earlier research by his colleagues detected genetic material from the COVID virus (viral RNA) in stool samples from children with multisystem inflammatory syndrome (a rare but serious condition that often strikes around four weeks after catching COVID) as well as spike protein and a marker of gut leakiness in their blood.”
Long COVID—also known as long-haul COVID, post-COVID-19, or its technical name, post-acute sequelae of COVID-19 or PASC—can involve health problems continuing weeks, months, or even years after a positive diagnosis, according to the federal Centers for Disease Control and Prevention (CDC).
Symptoms of long COVID, according to the researchers, include:
fatigue,
loss of smell,
memory loss,
gastrointestinal distress, and
shortness of breath.
“If someone could somehow get to that viral load and eliminate it, it might lead to resolution of symptoms,” Walt told the Boston Globe, which noted that the researchers may explore a clinical trial involving antiviral drugs for treatment of long COVID-19.
Clues from Earlier Studies on Long COVID-19
Medical conditions that persisted following a COVID-19 infection have been studied for some time. In fact, in an earlier study, Walt and others found children who developed a multisystem inflammation syndrome weeks after being infected by SARS-CoV-2, according to their 2021 paper published in The Journal of Clinical Investigation, titled, “Multisystem Inflammatory Syndrome in Children Is Driven by Zonulin-Dependent Loss of Gut Mucosal Barrier.”
Although these earlier studies provided clues, the cause of PASC remains unclear, the researchers noted. They planned to take a more precise look at PASC biology by using appropriate sampling and patient recruitment.
“Disentangling the complex biology of PASC will rely on the identification of biomarkers that enable classification of patient phenotypes. Here, we analyze plasma samples collected from PASC and COVID-19 patients to determine the levels of SARS-CoV-2 antigens and cytokines and identify a blood biomarker that appears in the majority of PASC patients,” the researchers wrote.
Finding a Marker of a Persistent Infection
The researchers used plasma samples from 63 people with a previous SARS-CoV-2 diagnosis (37 also had PASC), Medical News Today reported. Over a 12-month period, the researchers’ findings included:
Detection in 65% of PASC samples of full-length spike, S1 spike, and nucleocapsid throughout the year of testing.
Spike detected in 60% of PASC patient samples, and not found in the COVID-19 samples.
In an interview with Scientific American, bioengineer Zoe Swank PhD, post-doctoral researcher, Brigham and Women’s Hospital, and co-author of the study, said, “Our main hypothesis is that the spike protein is not causing the symptoms, but it’s just a marker that is released because you still have infection of some cells with SARS-CoV-2.”
In that article, Swank shared the scientists’ intent to do more research involving hundreds of samples over the course of the COVID-19 pandemic from many hospitals and people.
COVID-19 Not the Only Virus That Hangs On
Having a long-haul COVID-19 marker is a “game-changer,” according to an infectious disease expert who was not involved in the study.
“There has not so far been a clear, objective marker that is measurable in the blood of people experiencing long COVID-19,” Michael Peluso, MD, Assistant Professor, Medicine, University of California San Francisco, told Scientific American. “I hope their findings will hold up. It really would make a difference for a lot of people if a marker like this could be validated,” he added.
However, COVID-19 is not the only virus that could persist. Ebola also may linger in areas that skirt the immune system, such as the eye interior and central nervous system, according to a World Health Organization fact sheet.
Thus, medical laboratory leaders may want to follow the Brigham and Women’s Hospital research to see if the scientists validate their finding, discover a biomarker for long-haul COVID-19, and pursue a clinical trial for antiviral drugs. Such discoveries could have implications for how diagnostic professionals work with physicians to care for long COVID patients.
Clinical laboratories continue to report positive COVID-19 tests for individuals that have been vaccinated and even previously infected with the same variant of the coronavirus
Researchers across the globe continue to study the SARS-CoV-2 coronavirus and its many variants. Their goals are to curb the spread of the disease and develop new therapies and treatments for optimal patient outcomes. Now, a study conducted by scientists at the University of Missouri (UM) provides deeper insight into the processes the virus uses to mutate and overpower the human immune system. These findings could lead to improved antivirals and clinical laboratory tests for COVID-19.
The UM team identified specific mutations occurring within the virus’ spike protein that help Omicron subvariants evade existing antibodies and create an infection. These mutations may explain why some people who have had previous COVID-19 infections and/or who are fully vaccinated continue to test positive for SARS-CoV-2, and why the virus continues to evolve.
“Omicron now has more than 130 sublineages and they have been here for quite a while. We are now just finally able to detect them and differentiate among them with this research,” said Kamlendra Singh, PhD, associate research professor in the Department of Veterinary Pathobiology at UM’s College of Veterinary Medicine, in a UM press release.
“Previous variants, including Alpha, Beta, Gamma, and Delta, contributed to many of the mutations occurring now with these Omicron variants. So, our research shows how the virus has evolved over time with new mutations,” he added.
“Throughout the pandemic, the [SARS-CoV-2] virus has continued to get smarter and smarter. Even with vaccines, it continues to find new ways to mutate and evade existing antibodies,” said Kamlendra Singh, PhD (above), Associate Research Professor, College of Veterinary Medicine at University of Missouri, in a UM press release. This research team’s findings may help clinical laboratories further develop their SARS-CoV-2 antibody tests. (Photo copyright: University of Missouri.)
Antibodies for One Variant, but Not for Another
The scientists began their investigation by researching online databases that track COVID-19 cases and analyzing the protein sequences from more than 10 million Omicron-related samples that were collected from around the world since November of last year.
They examined the available sequences, structures of spike/receptor and spike/antibody complexes of the samples, and then conducted molecular dynamics simulations. The team utilized 3D modeling to locate where mutations occur and created structures of the spike protein to determine how the mutations are affected by antibodies and vaccinations.
The researchers found that the Omicron variant continues to mutate and has become extremely efficient at adaptation. Reinfections are happening because many individuals do not possess the antibodies for the new subvariants that continue to develop.
“Vaccinated individuals, or those who have previously tested positive, may have the antibodies for one variant but not necessarily for any of the other variants,” Singh explained. “The various mutations may seem like only subtle differences, but they are very important.”
The UM scientists’ research shows it is possible to differentiate Omicron subvariants from each other and pinpoint how certain mutations might become problematic for patients. According to Singh, many people can be infected with multiple variants at the same time. He is hopeful that their work will make it possible for vaccines and other treatments to specifically target different strains of the virus.
Singh also believes that the coronavirus is most likely never going to disappear from society and that new variants and their sublineages will continue to appear and evolve.
“The ultimate solution going forward will likely be the development of small molecule, antiviral drugs that target parts of the virus that do not mutate,” Singh said. “While there is no vaccine for HIV, there are very effective antiviral drugs that help those infected live a healthy life, so hopefully the same can be true with COVID-19.”
Omicron Subvariants May Be Here to Stay
“I am proud of my team’s efforts, as we have identified specific mutations for various variants throughout the pandemic, and it feels good to be contributing to research that is assisting with the situation,” Singh said. “We will continue to help out, as there will surely be new variants in the future.”
Singh is also part of a team that developed a supplement called CoroQuil-Zn, which was designed to reduce a patient’s viral load after being infected with SARS-CoV-2. The drug is currently being used in parts of India and is awaiting approval from the US Food and Drug Administration (FDA).
Clinical laboratories that perform antibody testing for SARS-CoV-2 infections should be aware that the coronavirus will likely be moving among humans for many years to come. This recent research may aid in the development of new antivirals, treatments, and vaccines that target specific subvariants for the best patient outcomes.
Many of the mutations were found at sites on the spike protein where antibodies bind, which may explain why the Omicron variant is more infectious than previous variants
Scientists at the University of Missouri (UM) now have a better understanding of why the SARS-CoV-2 Omicron variant is more infectious than previous variants and that knowledge may lead to improved antivirals and clinical laboratory tests for COVID-19.
As the Omicron variant of the coronavirus spread across the globe, scientists noted it appeared to be more contagious than previous variants and seemed resistant to the existing vaccines. As time went by it also appeared to increase risk for reinfection.
The UM researchers wanted to know why. They began by examining the Omicron variant’s mutation distribution, its evolutionary relationship to previous COVID-19 variants, and the structural impact of its mutations on antibody binding. They then analyzed protein sequences of Omicron variant samples collected from around the world.
“We know that viruses evolve over time and acquire mutations, so when we first heard of the new Omicron variant, we wanted to identify the mutations specific to this variant,” said Kamlendra Singh, PhD, Associate Research Professor, Department of Veterinary Pathobiology at UM’s College of Veterinary Medicine (CVM), in a UM press release.
Kamlendra Singh, PhD (above), an associate research professor in the Department of Veterinary Pathobiology at UM’s College of Veterinary Medicine, led the team that identified 46 mutations of the SARS-CoV-2 Omicron variant. “I went to India last April and I got infected by the Delta variant. So, it then became personal to me,” he told NBC affiliate KOMU. The UM team hopes their findings lead to improvements in existing COVID-19 antivirals and clinical laboratory tests. (Photo copyright: University of Missouri.)
In their paper, the UM team wrote, “Here we present the analyses of mutation distribution, the evolutionary relationship of Omicron with previous variants, and probable structural impact of mutations on antibody binding. … The structural analyses showed that several mutations are localized to the region of the S protein [coronavirus spike protein] that is the major target of antibodies, suggesting that the mutations in the Omicron variant may affect the binding affinities of antibodies to the S protein.”
There are a total of 46 highly prevalent mutations throughout the Omicron variant.
Twenty-three of the 46 mutations belong to the S protein (more than any previous variant).
Twenty-three of 46 is a markedly higher number of S protein mutations than reported for any SARS-CoV-2 variant.
A significant number of Omicron mutations are at the antibody binding surface of the S protein.
“Mutation is change in the genome that results in a different type of protein,” Singh told NBC affiliate KOMU. “Once you have different kinds of protein after the virus and the virus attacks the cell, our antibodies do not recognize that, because it has already been mutated.”
Omicron Mutations Interfere with Antibody Binding
Of the 46 Omicron variant mutations discovered by the UM researchers, some were found in areas of the coronavirus’ spike protein where antibodies normally bind to prevent infection or reinfection.
“The purpose of antibodies is to recognize the virus and stop the binding, which prevents infection,” Singh explained. “However, we found many of the mutations in the Omicron variant are located right where the antibodies are supposed to bind, so we are showing how the virus continues to evolve in a way that it can potentially escape or evade the existing antibodies, and therefore continue to infect so many people.”
These findings explain how the Omicron variant bypasses pre-existing antibodies in a person’s blood to cause initial infection as well as reinfection.
The UM team hopes their research will help other scientists better understand how the SARS-CoV-2 coronavirus has evolved and lead to future clinical laboratory antiviral treatments.
“The first step toward solving a problem is getting a better understanding of the specific problem in the first place,” Singh said. “It feels good to be contributing to research that is helping out with the pandemic situation, which has obviously been affecting people all over the world.”
Singh and his team have developed a supplement called CoroQuil-Zn designed to reduce a patient’s viral load after being infected with the SARS-CoV-2 coronavirus. The drug is currently being used in parts of India and is awaiting approval from the US Food and Drug Administration (FDA).
New discoveries about SARS-CoV-2 and its variants continue to further understanding of the coronavirus. Research such as that performed at the University of Missouri may lead to new clinical laboratory tests, more effective treatments, and improved vaccines that could save thousands of lives worldwide.
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.
Fear that immunity-resistant mutations of SARS-CoV-2 will emerge are real and the scientific community is paying close attention
Detection of an increasing number of new variants of the SARS-CoV-2 coronavirus raises the possibility that a new strain of COVID-19 might emerge that brings new problems to the management of the pandemic. Public health officials and clinical laboratory scientists are on the alert to determine if any new COVID-19 variant is more virulent or more easily transmissible.
Pathologists, along with the rest of the scientific community worldwide, are following reports of increasing coronavirus mutations with growing concern. The Alpha variant (Lineage B.1.1.7) accounted for most of the COVID-19 cases in April of 2021 in the US, though it was first identified in the United Kingdom. That was followed by the Iota variant (Lineage B.1.526) first identified in New York City. A series of other variants were to follow. Scientists were not surprised. It is normal for viruses to mutate, so they logged and tracked the mutations.
Then, the Delta variant (Lineage B.1.617.2) emerged during a severe outbreak in India. At first, it did not seem more threatening than any other variant, but that changed very quickly. Delta was different.
“The speed with which it dominated the pandemic has left scientists nervous about what the virus will do next. The variant battles of 2021 are part of a longer war, one that is far from over,” The Washington Post reported, which added, “Today, [Delta] has nearly wiped out all of its rivals. The coronavirus pandemic in America has become a Delta pandemic. By the end of July, it accounted for 93.4% of new infections, according to the Centers for Disease Control and Prevention.”
Why is Delta the Worst COVID-19 Variant So Far?
The Delta variant has two advantages that scientists know about:
Stickier spike protein than the spike on the original SARS-CoV-2 coronavirus, as well as on the other, earlier variants. This means that the Delta variant stands a better chance of remaining in a person’s nose or throat long enough to reproduce.
Faster replication. When a virus mutation has more opportunity to reproduce, it quickly becomes the main viral strain. This is the case with the Delta variant. Experts say that the viral load in patients with Delta is around 1,000 times higher than in patients with the original virus.
The image above is a “Colorized scanning electron micrograph of an apoptotic cell (tan) heavily infected with SARS-COV-2 virus particles (orange), isolated from a patient sample,” Newsweek reported. (Photo copyright: National Institute of Allergy and Infectious Diseases/Newsweek.)
Will More Dangerous SARS-CoV-2 Variants Appear?
“The great fear is that nature could spit out some new variant that completely saps the power of vaccines and upends the progress we’ve made against the pandemic. But to virologists and immunologists, such a possibility seems very unlikely,” STAT reported.
That is because, unlike Influenza, which is also a coronavirus, SARS-CoV-2 variants are not able to share genetic materials and recombine into deadlier variants. Thus, scientists are skeptical that a variant could appear and wipe out the progress made with vaccines and treatments.
One of the reasons the Flu vaccine changes every year is Influenza’s ability to recombine into variants that can evade immunity. Therefore, scientists are beginning to suspect that SARS-CoV-2, like the Flu, will likely be around for a while.
“I don’t think eradication is on the table. But I think we could come up with something that’s better than what we have for the flu,” Sharone Green, MD, Associate Professor of Medicine, Division of Infectious Diseases and Immunology and Infection Control Officer at University of Massachusetts Medical School, told Newsweek.
Limiting Infections and Replication
Several factors combined to create the COVID-19 pandemic. But SARS-CoV-2 was a novel coronavirus, meaning it was a new pathogen of a known virus. This meant every person on the planet was a potential host.
The situation now is different. Thanks to natural immunity, vaccines, and treatments that shorten the infection, the SARS-CoV-2 coronavirus has less chance to replicate.
“The pressure is there, but the opportunity is not. The virus has to replicate in order to mutate, but each virus doesn’t get many lottery tickets in a vaccinated person who’s infected,” Jeremy Kamil, PhD, Associate Professor of Microbiology and Immunology at LSU Health in Shreveport, La., told STAT.
Tracking Variants of Interest and Variants of Concern
The World Health Organization (WHO) has been monitoring the viral evolution of SARS-CoV-2 since the beginning of the pandemic. In late 2020, the WHO created categories for tracking variants:
VOIs are “A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity.”
Current VOIs include:
Eta (Lineage B.1.525), detected in multiple countries, designated a VOI in March 2021.
Iota (Lineage B.1.526), US, first detected in November 2020, designated a VOI in March 2021.
Lambda (lineage C.37), Peru, first detected in December 2020, designated a VOI in June 2021.
VOCs, on the other hand, demonstrate all the characteristics of VOIs and also demonstrate “an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.”
Current VOCs include:
Alpha (lineage B.1.1.7), first detected in the UK, September 2020.
Delta (lineage B.1.617.2), first detected in India, October 2020.
Will Vaccines Stop Working?
With each new variant, there tends to be a flurry of media attention and fearmongering. That a variant could emerge which would render our current vaccines ineffective has the scientific community’s attention.
“There is intense interest in whether mutations in the spike glycoprotein mediate escape from host antibodies and could potentially compromise vaccine effectiveness, since spike is the major viral antigen in the current vaccines,” wrote Adam S. Lauring, MD, PhD, and Emma B. Hodcroft, PhD, in “Genetic Variants of SARS-CoV-2—What Do They Mean?” published in the Journal of the American Medical Association (JAMA).
“Because current vaccines provoke an immune response to the entire spike protein, it is hoped that effective protection may still occur despite a few changes at antigenic sites in SARS-CoV-2 variants,” they added.
Future events may justify the optimism that the ongoing effectiveness of vaccines will help with many COVID-19 variants. But pathologists and clinical laboratory leaders may want to be vigilant, because as infection rates increase, so do workloads and demands on critical resources in their medical laboratories.
