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Post-acute COVID-19 is characterized by gut viral antigen persistence in inflammatory bowel diseases, 2022, Zollner et al

Discussion in 'Long Covid research' started by LarsSG, May 2, 2022.

  1. LarsSG

    LarsSG Senior Member (Voting Rights)


    Background and aims:

    The coronavirus disease 2019 (COVID-19) pandemic affects populations, societies and lives for more than two years. Long-term sequelae of COVID-19, collectively termed the post-acute COVID-19 syndrome, are rapidly emerging across the globe. Here, we investigated whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) antigen persistence underlies the post-acute COVID-19 syndrome.


    We performed an endoscopy study with 46 inflammatory bowel disease (IBD) patients 219 days (range: 94-257) after a confirmed COVID-19 infection. SARS-CoV-2 antigen persistence was assessed in the small and large intestine by qPCR of four viral transcripts, immunofluorescence of viral nucleocapsid and virus cultivation from biopsy tissue. Post-acute COVID-19 was assessed by a standardized questionnaire, and a systemic SARS-CoV-2 immune response was evaluated by flow-cytometry and ELISA at endoscopy. IBD activity was evaluated by clinical, biochemical and endoscopic means.


    We report expression of SARS-CoV-2 RNA in the gut mucosa ~7 months after mild acute COVID-19 in 32 of 46 patients with IBD. Viral nucleocapsid protein persisted in 24 of 46 patients in gut epithelium and CD8+ T cells. Expression of SARS-CoV-2 antigens was not detectable in stool and viral antigen persistence was unrelated to severity of acute COVID-19, immunosuppressive therapy and gut inflammation. We were unable to culture SARS-CoV-2 from gut tissue of patients with viral antigen persistence. Post-acute sequelae of COVID-19 were reported from the majority of patients with viral antigen persistence, but not from patients without viral antigen persistence.


    Our results indicate that SARS-CoV-2 antigen persistence in infected tissues serves as a basis for post-acute COVID-19. The concept that viral antigen persistence instigates immune perturbation and post-acute COVID-19 requires validation in controlled clinical trials.

    Preprint PDF

    From the Discussion:
    We argue that viral antigen persistence reflects incomplete clearance of SARS-CoV-2 rather than subclinical (latent or persistent) infection, as we were unable to replicate virus from biopsy derived tissue. In line with this, we usually detected only some (but not all) viral transcripts in biopsies from the same patient. Our experimental data rather suggest that immunosuppressive therapy with or without genetic predisposition (affecting the immune system) may promote incomplete viral clearance.

    In our report, only patients with gut antigen persistence (determined by qPCR) reported post-acute COVID-19 symptoms. In contrast, none of the patients without evidence for antigen persistence in the gut reported symptoms of post-acute COVID-19. This observation strongly argues for a role of viral antigen persistence in post-acute COVID-19 and it appears plausible that SARS-CoV-2 antigen persistence, possibly in infected tissues beyond the gut, could impact host immune responses underlying the post-acute COVID-19 syndrome.

    Note: They asked patients about post-Covid symptoms, but it isn't clear to me if they asked patients specifically if they had symptoms that appeared or persisted post-Covid or asked them if they had symptoms in general, which they classified as post-Covid symptoms.
  2. Hutan

    Hutan Moderator Staff Member

    Thanks @LarsSG
    Seems like an important finding.

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  3. Boba

    Boba Established Member

    Interesting. They didn’t find any active virus, but remnants with all patients experiencing LC symptoms and the other way around didn’t find any remnants in the patients without LC symptoms. No healthy controls obviously. Would be interesting to see if really healthy controls don’t show remnants as well.

    Would explain why postvax long haulers have symptoms. They should check those as well for particles. Then obviously the question of pathology connected to those particles.
  4. Hutan

    Hutan Moderator Staff Member

    To me, this idea makes some sense. I think the strongest argument I've heard against this idea of persistence of pathogen antigens is that the antigens would break down over time, the body would recycle and eliminate them. So, perhaps it might work for an illness of months or even a few years, but it becomes less likely for illnesses lasting 5 years or decades. That's when the idea of smouldering infections that periodically flare up gets invoked.

    I thought the paper was good. They were looking at biopsies of patients with a previous diagnosis of IBD, so perhaps their gut lining was a bit fragile or unusual, although it sounded as though many were in remission at the time of the biopsies. It would have been good to have a bit more clarity around symptoms regarded as indicative of Long Covid.

    There's the potential confounding of reinfections, possibly asymptomatic reinfections. That's going to confound other similar studies looking at even longer periods since the initial infection unless it's possible to identify specific variants from the viral fragments.
    Boba, Trish and Wyva like this.

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