Serum Level of Anti-Nucleocapsid, but Not Anti-Spike Antibody, Is Associated with Improvement of Long COVID Symptoms (Varnai et al, 2022)

[Consul]

Abstract

Background: Long COVID is a condition characterized by long-term sequelae persisting after the typical convalescence period of COVID-19. Previous reports have suggested the role of an unsatisfactory immune response and impaired viral clearance in the pathogenesis of long COVID syndrome. We focused on potential associations between post-vaccination changes of antibody titers and the severity of long COVID symptoms and factors influencing the state of remission observed in patients with long COVID after vaccination. Methods: The severity of long COVID symptoms and serum anti-SARS-CoV-2 spike (S-Ig) and nucleocapsid (NC-Ig) levels were assessed in 107 post-COVID subjects at two time points: at baseline, and 17–24 weeks later. Besides, vaccination status was also assessed. Symptoms were evaluated based on the Chalder fatigue scale (CFQ-11) and visual analogue scale (VAS). Results: Serum level of S-Ig and NC-Ig at baseline were significantly higher in the patients with non-severe fatigue than those with severe fatigue, and this difference remained significant at follow-up in the case of NC-Ig. NC-Ig level above median was as an independent predictor for complete remission at follow-up. The difference in NC-Ig levels in subgroup analyses (severe fatigue vs. non-severe fatigue; complete remission vs. incomplete remission or progression) was found to be significant only in patients who received vaccination. Conclusions: The immune response against the SARS-CoV-2 nucleocapsid may play a more important role than the spike in the course of long-term COVID syndrome.


Discussion:

[...]
In general, one of the main theories is the insufficient clearance of viral fragments. The patients who have low levels of antibodies at the time of hospital discharge may have a high risk of developing redetectable SARS-CoV-2 RNA on RT-PCR testing after recovery. These findings indicate the important role of these antibodies in viral clearance [10]. SARS-CoV2 nucleocapsid protein has RNA-binding and chaperone activities and promotes SARS-CoV-2 gRNA replication [11]; thus, an inadequate humoral immune response (against nucleocapsid antigen) may indirectly promote further viral replication and lead to further partial persistence of symptoms. [...]

The study: https://www.mdpi.com/2076-393X/10/2/165/htm

 

[Pyrrhus]

NC-Ig level above median was as an independent predictor for complete remission at follow-up. The difference in NC-Ig levels in subgroup analyses (severe fatigue vs. non-severe fatigue; complete remission vs. incomplete remission or progression) was found to be significant only in patients who received vaccination.

So low levels of anti-coronavirus antibodies might predispose someone to developing Long Covid. (not counting the anti-spike antibodies which could be due to vaccination)

The patients who have low levels of antibodies at the time of hospital discharge may have a high risk of developing redetectable SARS-CoV-2 RNA on RT-PCR testing after recovery. These findings indicate the important role of these antibodies in viral clearance

an inadequate humoral immune response (against nucleocapsid antigen) may indirectly promote further viral replication and lead to further partial persistence of symptoms.

And one reason why low levels of anti-coronavirus antibodies might predispose someone to developing Long Covid is because the low levels of antibodies allows the coronavirus to persist longer.

 

[Consul]

@Pyrrhus well they have some models in there that is supposed to show the importance of NC-IG but i cant judge whether or not these models are made out of thin air just to eek out a nice looking result for themselves. Would be pretty huge if true though but certainly total coronavirus-ig is the more down to earth assumption of what is driving LC.