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.
Company says it will offer five diagnostic tests that are useful to the public and some of these tests are among the highest volume tests performed by clinical labs
Heading to market is another device that works with a smartphone to provide consumers with a way to perform five popular medical laboratory tests. The product was developed by Cue, Inc., which describes itself as an entrepreneurial mobile diagnostics developer.
Cue is an at-home lab test device targeted at consumers. It will be priced at about $300, noted a report published by MobiHealthNews.
“We’re very interested in putting the power of the lab into the consumer’s hands in this new way,” said Clint Sever, Cue Cofounder and Chief Product Officer. However, pending Food and Drug Administration (FDA) clearance, Cue’s device is being presold under an “investigational exception” for $199, with promise of delivery in spring 2015.
Cue Allows Consumers to Perform Five Routine Lab Tests at Home
Initially, Cue will perform tests for influenza; testosterone; vitamin D; C-reactive protein (a marker for inflammation); and luteinizing hormone (an indicator of a women’s fertility) But that is just for starters.
According to Ayub Khattak, Cue Cofounder and CEO, the company plans to add more medical lab tests in the future. “The large majority of tests you do in the [clinical] lab today, we want to give you access to in your home,” he declared.
Ayub Khattak (pictured above), Cue Cofounder and CEO, says the Cue device will initially preform five routine tests, but other lab tests will be available in the future, (Photo copyright Cue)
In its blog about Cue, IEE Spectrum noted that the first five clinical laboratory tests the company designed to run on its device were selected because these are the most common tests run by labs and, therefore, are the most useful to the public. Sever and Khattak observed in the MobiHealthNews story that all of these tests—except the influenza test—are used in monitoring a patient’s condition and are done regularly.
Athletes and older men, for instance, want to keep tabs on their testosterone levels. People are interested in Vitamin D because it affects mood. Clinical laboratories perform 70-million Vitamin D yearly, according to Khattak. Inflammation is both a predictor of heart disease and a counter indicator for intense workouts, so if the tests indicated elevated C-reactive protein, a person may want to back off from exercise for a little while, he added. The test for luteinizing hormone tells a woman when she is likely to conceive.
The influenza test, on the other hand, allows parents or other caretakers to check for flu at home, similar to taking a child’s temperature. Sever emphasized that the flu test isn’t meant to replace a doctor visit. “It just gives you more information so you can have an informed conversation with your doctor,” he said.
How the Cue Device Works
The Cue device is about the size of a Rubik’s cube. The test cartridges are about the size of a matchbox. Each cartridge uses blood, saliva, or mucus samples to conduct home lab tests. Each cartridge contains microfluidic channels and the necessary reagents for the test to be performed.
When the cartridge is inserted, Cue prompts the user to collect a sample with the sample wand that is included with the device, explained the IEE Spectrum blog. The testosterone test requires a saliva specimen. The flu test uses a nasal swab, and the other tests require a drop of blood as the specimen.
Once the sample wand is inserted into the cartridge, the reagents combine with the sample inside the cartridge. A sensor then looks for the target molecule, such as testosterone or Vitamin D, and detects the quantity or level. Cue sends this information via Bluetooth to the user’s iPhone or Android smartphone. The smartphone app allows the user to track results over time, and offers suggestions for improving health status. For example, Sever said Cue might recommend specific foods or exercise to boost low testosterone level.
Can Cue Produce More Accurate Tests Than Clinical Laboratories?
Khattak can’t make claims about the accuracy of Cue’s technology because it hasn’t yet been cleared by the FDA, noted the MobiHealthNews story. But the devices inventors believe that Cue tests have the potential to be more accurate than those performed in clinical laboratories, because the human error factor is eliminated.
“What we’ve done is we simplified and automated the whole process,” explained Khattak. “So whereas a lab technician might have 10 steps and they might do 10 of them quite well, those little errors in each of the steps add up. And human error is the largest cause of variation and deviation from standard reproducible results… With us, it is one step. You add the sample, and then you get your results.”
Cue, a modular, Rubik-cube-sized device, uses simple microfluidic laboratory technology to perform five different medical laboratory tests that people routinely have done, including testosterone and vitamin D levels, inflammation, fertility and influenza. The device is being presold under an investigational exception to consumers for $199, with promise of delivery in spring 2015. Once approved by the FDA, the price will be $300. (Photo copyright Cue)
Investors are Successful Tech Entrepreneurs and Diagnostics Experts
Clinical laboratory managers might find it interesting that Cue investors are successful entrepreneurs with expertise in both diagnostics and digital technologies. The investor group includes two University of California, Los Angeles (UCLA) professors, as well as an anonymous private investor, noted MobiHealthNews.
The other founder is Patrick Soon-Shiong, M.D., a former UCLA Medical Professor, who currently serves on the advisory board of UCLA Engineering’s Institute for Technology Advancement. Known as “LA’s billionaire doctor,” Soon-Shiong, a surgeon-turned-entrepreneur, is co-inventor on more than 40 U.S. and foreign patents and has sold two successful businesses for $8.5 billion.
Last year, Soon-Shiong launched Los Angeles-based Nantworks, LLC, a company that aims to revolutionize medicine by adding “Big Data” to patient care. Soon-Shiong also serves as Providence Health & Services’ Director for Cancer Services and Bioinformatics.
Will Consumers Pay for a Device that Does Medical Lab Tests at Home?
Will consumers be willing to pay $199 for a medical laboratory testing device that hooks up to their smartphone or tablet PC? The founders of Cue will find out next year, assuming that FDA clearance is forthcoming and the device reaches the market. Also, will Cue perform medical lab tests with accuracy that is comparable with that of the nation’s best clinical laboratories? There are many pathologists and lab scientists who will be prepared to challenge that statement.
