Share on PinterestScientists may have identified a potential biomarker for prolonged COVID. Hollie Adams/Bloomberg via Getty ImagesThe researchers investigated the antigens of SARS-CoV-2, the virus that causes COVID-19, present in blood plasma samples collected from people with prolonged COVID infection and typical COVID-19 infection.They found that one particular SARS-CoV-2 antigen, the spike protein, was present in the blood of most long-term COVID patients, up to a year after they were first diagnosed with COVID-19.However, in patients with typical COVID-19 infection, the spike protein was not detected. This finding provides evidence for the hypothesis that SARS-CoV-2 may persist in the body through viral reservoirs, where it continues to release proteins and trigger inflammation.
Current data from the World Health Organization (WHO) indicates that about 1 in 4 people with COVID-19 continue to experience symptoms 4 to 5 weeks after diagnosis, and about 1 in 10 have ongoing symptoms after 12 weeks. weeks.
People with post-acute sequelae of COVID-19 (PASC), or prolonged COVID, have reported a variety of symptoms, including but not limited to fatigue, anosmia (loss of sense of smell), memory loss, gastrointestinal upset, and shortness of breath.
The underlying mechanism of long COVID is complicated. The identification of a blood biomarker for long COVID, or in other words, a biological molecule that appears in the blood of most long COVID patients, could contribute to a better understanding of the biology of long COVID.
A new study finds evidence of a biomarker that could point towards an active viral reservoir in the body, particularly in the gut after initial SARS-CoV-2 infection.
A preprint of the study was published on medRxiv.
To identify a blood biomarker for long-term COVID, researchers at Harvard Medical School and the Ragon Institute at MGH, MIT, and Harvard analyzed blood plasma samples collected from patients with long-term COVID and typical COVID-19 infection over a period of time. 12 months.
They sought to determine the levels of three SARS-CoV-2 antigens:
Spike protein: spike-shaped molecules that protrude from the surface of the SARS-CoV-2 virus Spike protein subunit S1: one of two subunits that make up the spike protein Nucleocapsid: nucleic acid (genetic material) and surrounding capsid (cover of protein) of the virus
The researchers found that the spike protein, S1 subunit, or nucleocapsid was present in the blood of 65% of long-COVID patients they tested, up to 12 months after their initial COVID-19 infection.
Of the three SARS-CoV-2 antigens, the spike protein was the most common, being detected in 60%, or 3 out of 5, of long-COVID patients.
In contrast, the researchers did not detect spike protein in any of the patients with typical COVID-19 infection. The S1 subunit and nucleocapsid were detected in the blood of COVID-19 patients immediately after COVID-19 diagnosis, but the levels of these antigens quickly fell below the limit of detection.
“The most logical interpretation [of the data presented in the pre-print] is that spike protein in the serum is a surrogate marker for a persistent infection somewhere in the body,” John P. Moore, MD, professor of microbiology and immunology at Weill Cornell Medicine, who was not involved in the study, told Medical News Today. the study.
The researchers believe that the presence of SARS-CoV-2 spike protein in most patients with prolonged COVID up to 12 months after diagnosis suggests the presence of a persistent active viral reservoir of SARS-CoV-2.
Dr. David R. Walt, one of the study’s authors, told The Guardian that the presence of the spike protein indicated that the half-life of this antigen is “pretty short” in the body.
Dr. Andrew Pekosz, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, who was not involved in the study, told MNT that the existence of SARS-CoV-2 reservoirs in organs such as the intestine could potentially explain the symptoms of prolonged COVID.
The presence of virus-infected cells at low levels […] it would be the “trigger” for the continuous activation of the immune system. Finding these viral proteins in the blood could also explain why multiple organs can be affected by prolonged COVID. This type of persistent infection is seen with some viruses, but has not been clearly demonstrated with SARS-CoV-2.”
– Dr Andrew Pekosz
Other researchers have also found evidence of viral persistence (the continued presence of the virus) in patients with prolonged COVID symptoms.
Dr. Akiko Iwasaki, a distinguished professor of immunobiology and molecular, cell, and developmental biology at Yale University, who was not involved in the study, told MNT:
“Evidence for persistent viruses and viral RNA/antigen reservoirs [is] more and more frequent […] The presence of the spike protein in circulation in long-distance vehicles adds to this emerging evidence.”
Studies have pointed to the intestine as a possible reservoir.
At Stanford University in California, Dr. Ami S. Bhatt and colleagues found that about 4% of people (or 1 in 25) with mild to moderate COVID-19 continued to shed viral RNA in their stool seven months after diagnosis of COVID-19.
People with detectable viral RNA in their stool also reported ongoing gastrointestinal symptoms, including abdominal pain, nausea, and vomiting.
In addition to providing compelling evidence for the long-COVID viral reservoir hypothesis, the presence of spike protein in most long-standing COVID patients suggests that spike protein could potentially be used as a biomarker for long-standing COVID. Allowing doctors to diagnose prolonged COVID through a blood plasma test is a step toward more effective treatment.
However, before drawing solid conclusions, researchers will need to conduct more studies to confirm.
One question to answer is why 35-40% of long COVID patients had no measurable spike protein in their blood.
“Does this mean your symptoms stem from more than just long-term COVID or does it mean long-term COVID is the result of a multiplicity of causes? From our studies, we can’t answer that question,” Walt told MNT.
Dr. Pekosz described the study as “interesting,” but cautioned that more research is needed to truly understand its implications.
“The big questions are really, is this enough [spike] protein to be trigger [long COVID] symptom? Would treatments such as antivirals or booster shots eliminate these sources of viral protein and thus alleviate [long COVID] symptom? Where are these infected cells and how do the virus proteins get into the blood? he said.
Source: www.medicalnewstoday.com