- Researchers investigated the antigens of SARS-CoV-2—the virus that causes COVID-19—current in blood plasma samples collected from people with lengthy COVID and typical COVID-19 an infection.
- They discovered that one specific SARS-CoV-2 antigen—the spike protein—was current within the blood of a majority of lengthy COVID sufferers, as much as a yr after they have been first identified with COVID-19.
- In sufferers with typical COVID-19 an infection, nevertheless, the spike protein was not detected.
- This discovering offers proof for the speculation that SARS-CoV-2 can persist within the physique by way of viral reservoirs, the place it continues to launch spike protein and set off irritation.
Present information from the World Well being Group (WHO) signifies that round 1 in 4 people with COVID-19 proceed to expertise signs 4–5 weeks after prognosis, and roughly 1 in 10 have persevering with signs after 12 weeks.
People with post-acute sequelae of COVID-19 (PASC), or lengthy COVID, have reported a variety of signs, together with, however not restricted to,
The underlying mechanism of lengthy COVID is sophisticated. Figuring out a blood biomarker for lengthy COVID, or in different phrases, a organic molecule that seems within the blood of most lengthy COVID sufferers, might contribute to a greater understanding of the biology of lengthy COVID.
A brand new examine finds proof of a biomarker that would level towards an lively viral reservoir within the physique, notably within the intestine after preliminary SARS-CoV-2 an infection.
A preprint of the examine was printed on medRxiv.
To determine a blood biomarker for lengthy COVID, researchers at Harvard Medical Faculty and the Ragon Institute of MGH, MIT and Harvard, analyzed blood plasma samples collected from sufferers with lengthy COVID and typical COVID-19 an infection over a interval of 12 months.
They sought to find out the degrees of three SARS-CoV-2 antigens:
- Spike protein – spike-like molecules that protrude from the floor of the SARS-CoV-2 virus
- S1 subunit of spike protein – certainly one of two subunits that make up the spike protein
- Nucleocapsid – nucleic acid (genetic materials) and surrounding capsid (protein coat) of the virus
The researchers discovered that the spike protein, S1 subunit, or nucleocapsid have been current within the blood of 65% of the lengthy COVID sufferers they examined, as much as 12 months after their preliminary COVID-19 an infection.
Out of the three SARS-CoV-2 antigens, the spike protein was the most typical, having been detected in 60%—or 3 out of 5—of lengthy COVID sufferers.
In distinction, the researchers didn’t detect spike protein in any of the sufferers with typical COVID-19 an infection. The S1 subunit and nucleocapsid have been detected within the blood of COVID-19 sufferers instantly after the COVID-19 prognosis, however the ranges of those antigens rapidly dropped beneath the restrict of detection.
“Essentially the most logical interpretation [of the data presented in the pre-print] is that spike protein in serum is a surrogate marker for a persistent an infection someplace within the physique,” Dr. John P. Moore, professor of microbiology and immunology at Weill Cornell Drugs, who was not concerned within the examine, instructed Medical Information At the moment.
The researchers imagine that the presence of SARS-CoV-2 spike protein in a majority of lengthy COVID sufferers as much as 12 months post-diagnosis suggests the presence of an lively persistent SARS-CoV-2 viral reservoir.
Dr. David R. Walt, one of many examine’s authors, instructed The Guardian that the presence of the spike protein indicated such a reservoir because the half-life of this antigen is “fairly brief” within the physique.
Dr. Andrew Pekosz, professor of molecular microbiology and immunology on the Johns Hopkins College Bloomberg Faculty of Public Well being, who was not concerned within the examine, instructed MNT that the existence of reservoirs of SARS-CoV-2 in organs such because the intestine might doubtlessly clarify the signs of lengthy COVID.
“The presence of virus-infected cells at low ranges […] could be the “set off” for continued activation of the immune system. Discovering these viral proteins within the blood might additionally clarify why a number of organs may be affected by lengthy COVID. This type of persistent an infection is seen with some viruses however has not been clearly demonstrated with SARS-CoV-2.”
– Dr. Andrew Pekosz
Different researchers have additionally discovered proof of viral persistence (the persevering with presence of the virus) in sufferers with lengthy COVID signs.
Dr. Akiko Iwasaki, sterling professor of immunobiology and molecular, mobile and developmental biology at Yale College, who was not concerned within the examine, instructed MNT:
“Proof for persistent virus and viral antigen/RNA reservoirs [is] turning into an increasing number of prevalent […] The presence of the spike protein in circulation in lengthy haulers is including to this rising proof.”
Research have pointed to the intestine as a attainable reservoir.
At Stanford College in California, Dr. Ami S. Bhatt and colleagues discovered that about
People with detectable viral RNA of their stools additionally reported ongoing gastrointestinal signs corresponding to belly ache, nausea and vomiting.
In addition to offering compelling proof for the viral reservoir speculation of lengthy COVID, the presence of spike protein within the majority of lengthy COVID sufferers means that spike protein might doubtlessly be used as a biomarker for lengthy COVID. Enabling clinicians to diagnose lengthy COVID by way of a blood plasma take a look at is a step towards more practical therapy.
Nevertheless, earlier than coming to stable conclusions, researchers might want to conduct additional research to verify.
One query to reply is why 35-40% of the lengthy COVID sufferers didn’t have measurable spike protein of their blood.
“Does this imply that their signs come up from one thing aside from lengthy COVID or does it imply that lengthy COVID outcomes from a multiplicity of causes? From our research, we are able to’t reply that query,” Walt instructed MNT.
Dr. Pekosz described the examine as “intriguing” however cautioned that extra investigation is required to really perceive its implication.
“The massive questions are actually, is that this sufficient [spike] protein to be triggering [long COVID] signs? Would therapies like antivirals or booster vaccinations get rid of these sources of viral protein and therefore relieve [long COVID] signs? The place are these contaminated cells situated and the way do the virus proteins get into the blood?” he mentioned.