Viral Antigen and Inflammatory Biomarkers in Cerebrospinal Fluid in Patients With COVID-19 Infection and Neurologic Symptoms Compared With Control Participants Without Infection or Neurologic Symptoms | Infectious Diseases | JN Learning | AMA Ed Hub [Skip to Content]
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Viral Antigen and Inflammatory Biomarkers in Cerebrospinal Fluid in Patients With COVID-19 Infection and Neurologic Symptoms Compared With Control Participants Without Infection or Neurologic Symptoms

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Key Points

Question  Are cerebrospinal fluid (CSF) SARS-CoV-2 antigens associated with central nervous system inflammation in patients with COVID-19?

Findings  Of 44 patients with COVID-19 (23 neurosymptomatic) included in this hospital-based cross-sectional study, CSF nucleocapsid antigen was detectable in 89% of patients with available data and was significantly correlated with immune activation markers (neopterin and interferon γ). Moreover, neurosymptomatic patients had a more pronounced inflammatory CSF profile compared with neuroasymptomatic patients that could not be attributed to differences in COVID-19 severity.

Meaning  These results suggest that viral components may contribute to central nervous system immune responses without direct viral invasion and highlight the clinical importance of neurologic symptoms.


Importance  Neurologic symptoms are common in COVID-19, but the central nervous system (CNS) pathogenesis is unclear, and viral RNA is rarely detected in cerebrospinal fluid (CSF).

Objective  To measure viral antigen and inflammatory biomarkers in CSF in relation to neurologic symptoms and disease severity.

Design, Setting, and Participants  This cross-sectional study was performed from March 1, 2020, to June 30, 2021, in patients 18 years or older who were admitted to Sahlgrenska University Hospital, Gothenburg, Sweden, with COVID-19. All patients had CSF samples taken because of neurologic symptoms or within a study protocol. Healthy volunteer and prepandemic control groups were included.

Exposure  SARS-CoV-2 infection.

Main Outcomes and Measures  Outcomes included CSF SARS-CoV-2 nucleocapsid antigen (N-Ag) using an ultrasensitive antigen capture immunoassay platform and CSF biomarkers of immune activation (neopterin, β2-microglobulin, and cytokines) and neuronal injury (neurofilament light protein [NfL]).

Results  Forty-four patients (median [IQR] age, 57 [48-69] years; 30 [68%] male; 26 with moderate COVID-19 and 18 with severe COVID-19 based on the World Health Organization Clinical Progression Scale), 10 healthy controls (median [IQR] age, 58 [54-60] years; 5 [50%] male), and 41 patient controls (COVID negative without evidence of CNS infection) (median [IQR] age, 59 [49-70] years; 19 [46%] male) were included in the study. Twenty-one patients were neuroasymptomatic and 23 were neurosymptomatic (21 with encephalopathy). In 31 of 35 patients for whom data were available (89%), CSF N-Ag was detected; viral RNA test results were negative in all. Nucleocapsid antigen was significantly correlated with CSF neopterin (r = 0.38; P = .03) and interferon γ (r = 0.42; P = .01). No differences in CSF N-Ag concentrations were found between patient groups. Patients had markedly increased CSF neopterin, β2-microglobulin, interleukin (IL) 2, IL-6, IL-10, and tumor necrosis factor α compared with controls. Neurosymptomatic patients had significantly higher median (IQR) CSF interferon γ (86 [47-172] vs 21 [17-81] fg/mL; P = .03) and had a significantly higher inflammatory biomarker profile using principal component analysis compared with neuroasymptomatic patients (0.54; 95% CI, 0.03-1.05; P = .04). Age-adjusted median (IQR) CSF NfL concentrations were higher in patients compared with controls (960 [673-1307] vs 618 [489-786] ng/L; P = .002). No differences were seen in any CSF biomarkers in moderate compared with severe disease.

Conclusions and Relevance  In this study of Swedish adults with COVID-19 infection and neurologic symptoms, compared with control participants, viral antigen was detectable in CSF and correlated with CNS immune activation. Patients with COVID-19 had signs of neuroaxonal injury, and neurosymptomatic patients had a more marked inflammatory profile that could not be attributed to differences in COVID-19 severity. These results highlight the clinical relevance of neurologic symptoms and suggest that viral components can contribute to CNS immune responses without direct viral invasion.

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Article Information

Accepted for Publication: April 4, 2022.

Published: May 23, 2022. doi:10.1001/jamanetworkopen.2022.13253

Correction: This article was corrected on June 22, 2022, to fix some incorrect labels in Figures 1 and 2; the label “Neurosymptomatic patients” had been incorrectly written as “Asymptomatic patients.”

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Edén A et al. JAMA Network Open.

Corresponding Author: Arvid Edén, MD, PhD, Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Sahlgrenska University Hospital, Gothenburg SE-416 50, Sweden (

Author Contributions: Dr Edén had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Edén, Schöll, Sigal, Stengelin, Gisslén.

Acquisition, analysis, or interpretation of data: Edén, Grahn, Bremell, Aghvanyan, Bathala, Fuchs, Gostner, Hagberg, Kanberg, Kanjananimmanont, Lindh, Misaghian, Nilsson, Sigal, Stentoft, Studahl, Yilmaz, Wang, Stengelin, Zetterberg, Gisslén.

Drafting of the manuscript: Edén, Gisslén.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Edén, Bathala, Misaghian, Nilsson, Wang, Gisslén.

Obtained funding: Edén, Schöll, Gisslén.

Administrative, technical, or material support: Bathala, Fuchs, Gostner, Kanberg, Kanjananimmanont, Lindh, Misaghian, Schöll, Sigal, Stentoft, Yilmaz, Wang, Stengelin, Gisslén.

Supervision: Edén, Grahn, Bremell, Sigal, Studahl, Gisslén.

Conflict of Interest Disclosures: Dr Schöll reported receiving grants from the Wallenberg Foundation, Swedish Research Council, and Swedish Brain Foundation during the conduct of the study. Dr Zetterberg reported receiving advisory board fees from AbbVie, Alector, Annexon, Artery Therapeutics, AZTherapies, CogRx, Denali, Eisai, Nervgen, Pinteon Therapeutics, Red Abbey Labs, Passage Bio, Roche, Samumed, Siemens Healthineers, Triplet Therapeutics, and Wave, lecture fees from Cellectricon, Roche, Fujirebio, Alzecure, and Biogen, and cofounding and owing stock in Brain Biomarker Solutions outside the submitted work. Dr Gisslén reported receiving grants from the Swedish state under an agreement between the Swedish government and the county councils, SciLifeLab from the Knut and Alice Wallenberg Foundation, and the Swedish Research Council during the conduct of the study. No other disclosures were reported.

Funding/Support: Dr Gisslén is supported by grants KAW 2020.0182 and KAW 2020.0241 from the SciLifeLab National COVID-19 Research Program, financed by the Knut and Alice Wallenberg Foundation, the Swedish state, under agreement ALFGBG-717531 between the Swedish government and the county councils and agreement 2021-06545 of the Swedish Research Council. Dr Zetterberg is a Wallenberg Scholar supported by grant 2018-02532 from the Swedish Research Council, grant 681712 from the European Research Council, grant ALFGBG-720931 from the Swedish State Support for Clinical Research, grant 201809-2016862 from the Alzheimer Drug Discovery Foundation, grants ADSF-21-831376-C, ADSF-21-831381-C, and ADSF-21-831377-C from the AD Strategic Fund, the Alzheimer's Association, the Olav Thon Foundation, the Erling-Persson Family Foundation, grant FO2019-0228 from the Stiftelsen för Gamla Tjänarinnor, Hjärnfonden, Sweden, the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement 860197, grant JPND2021-00694 from the European Union Joint Program for Neurodegenerative Disorders, and the UK Dementia Research Institute at UCL. Dr Schöll is supported by grant KAW2014.036 from the Knut and Alice Wallenberg Foundation (Wallenberg Centre for Molecular and Translational Medicine), grants 2017-02869, 2021-02678, and 2021-06545 from the Swedish Research Council, the Swedish state under the agreement between the Swedish government and the county councils, ALF agreements ALFGBG-813971 and ALFGBG-965326, and grants FO2021-0311 from the Swedish Brain Foundation.

Role of the Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Meeting Presentation: Presented at the Conference on Retroviruses and Opportunistic Infections (CROI) 2022 (virtual); February 16, 2022.

Frontera  JA , Sabadia  S , Lalchan  R ,  et al.  A prospective study of neurologic disorders in hospitalized COVID-19 patients in New York City.   Neurology. 2021;96(4):e575-e586. doi:10.1212/WNL.0000000000010979PubMedGoogle ScholarCrossref
Liotta  EM , Batra  A , Clark  JR ,  et al.  Frequent neurologic manifestations and encephalopathy-associated morbidity in Covid-19 patients.   Ann Clin Transl Neurol. 2020;7(11):2221-2230. doi:10.1002/acn3.51210 PubMedGoogle ScholarCrossref
Meppiel  E , Peiffer-Smadja  N , Maury  A ,  et al; contributors to the NeuroCOVID registry.  Neurologic manifestations associated with COVID-19: a multicentre registry.   Clin Microbiol Infect. 2021;27(3):458-466. doi:10.1016/j.cmi.2020.11.005PubMedGoogle ScholarCrossref
Edén  A , Simrén  J , Price  RW , Zetterberg  H , Gisslén  M .  Neurochemical biomarkers to study CNS effects of COVID-19: a narrative review and synthesis.   J Neurochem. 2021;159(1):61-77. doi:10.1111/jnc.15459 PubMedGoogle ScholarCrossref
Solomon  T .  Neurological infection with SARS-CoV-2—the story so far.   Nat Rev Neurol. 2021;17(2):65-66. doi:10.1038/s41582-020-00453-w PubMedGoogle ScholarCrossref
Brann  DH , Tsukahara  T , Weinreb  C ,  et al.  Non-neuronal expression of SARS-CoV-2 entry genes in the olfactory system suggests mechanisms underlying COVID-19-associated anosmia.   Sci Adv. 2020;6(31):eabc5801. doi:10.1126/sciadv.abc5801 PubMedGoogle ScholarCrossref
Meinhardt  J , Radke  J , Dittmayer  C ,  et al.  Olfactory transmucosal SARS-CoV-2 invasion as a port of central nervous system entry in individuals with COVID-19.   Nat Neurosci. 2021;24(2):168-175. doi:10.1038/s41593-020-00758-5PubMedGoogle ScholarCrossref
Thakur  KT , Miller  EH , Glendinning  MD ,  et al.  COVID-19 neuropathology at Columbia University Irving Medical Center/New York Presbyterian Hospital.   Brain. 2021;144(9):2696-2708. doi:10.1093/brain/awab148 PubMedGoogle ScholarCrossref
Lewis  A , Frontera  J , Placantonakis  DG ,  et al.  Cerebrospinal fluid in COVID-19: a systematic review of the literature.   J Neurol Sci. 2021;421:117316. doi:10.1016/j.jns.2021.117316 PubMedGoogle ScholarCrossref
Eden  A , Kanberg  N , Gostner  J ,  et al.  CSF biomarkers in patients with COVID-19 and neurological symptoms: a case series.   Neurology. 2021;96(2):e294-e300. PubMedGoogle Scholar
Pilotto  A , Masciocchi  S , Volonghi  I ,  et al.  SARS-CoV-2 encephalitis is a cytokine release syndrome: evidences from cerebrospinal fluid analyses.   Clin Infect Dis. 2021;73(9):e3019-e3026. doi:10.1093/cid/ciaa1933 PubMedGoogle ScholarCrossref
Virhammar  J , Naas  A , Fallmar  D ,  et al.  Biomarkers for central nervous system injury in cerebrospinal fluid are elevated in COVID-19 and associated with neurological symptoms and disease severity.   Eur J Neurol. 2021;28(10):3324-3331. doi:10.1111/ene.14703PubMedGoogle ScholarCrossref
Garcia  MA , Barreras  PV , Lewis  A ,  et al; Hopkins Neuro-COVID-19 Group.  Cerebrospinal fluid in COVID-19 neurological complications: neuroaxonal damage, anti-SARS-Cov2 antibodies but no evidence of cytokine storm.   J Neurol Sci. 2021;427:117517. doi:10.1016/j.jns.2021.117517 PubMedGoogle ScholarCrossref
Paterson  RW , Benjamin  LA , Mehta  PR ,  et al; UCLH Queen Square COVID-19 Biomarker Study Group.  Serum and cerebrospinal fluid biomarker profiles in acute SARS-CoV-2-associated neurological syndromes.   Brain Commun. 2021;3(3):fcab099. doi:10.1093/braincomms/fcab099 PubMedGoogle ScholarCrossref
Wang  H , Hogan  CA , Verghese  M ,  et al.  SARS-CoV-2 nucleocapsid plasma antigen for diagnosis and monitoring of COVID-19.   Clin Chem. 2021;68(1):204-213. doi:10.1093/clinchem/hvab216 PubMedGoogle ScholarCrossref
World Medical Association.  World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects.   JAMA. 2013;310(20):2191-2194. doi:10.1001/jama.2013.281053PubMedGoogle ScholarCrossref
Yilmaz  A , Marklund  E , Andersson  M ,  et al.  Upper respiratory tract levels of severe acute respiratory syndrome coronavirus 2 RNA and duration of viral RNA shedding do not differ between patients with mild and severe/critical coronavirus disease 2019.   J Infect Dis. 2021;223(1):15-18. doi:10.1093/infdis/jiaa632 PubMedGoogle ScholarCrossref
WHO Working Group on the Clinical Characterisation and Management of COVID-19 infection.  A minimal common outcome measure set for COVID-19 clinical research.   Lancet Infect Dis. 2020;20(8):e192-e197. doi:10.1016/S1473-3099(20)30483-7 PubMedGoogle ScholarCrossref
Yilmaz  A , Mellgren  Å , Fuchs  D ,  et al.  Switching from a regimen containing abacavir/lamivudine or emtricitabine/tenofovir disoproxil fumarate to emtricitabine/tenofovir alafenamide fumarate does not affect central nervous system HIV-1 infection.   Infect Dis (Lond). 2019;51(11-12):838-846. doi:10.1080/23744235.2019.1670352 PubMedGoogle ScholarCrossref
Hagberg  L , Cinque  P , Gisslen  M ,  et al.  Cerebrospinal fluid neopterin: an informative biomarker of central nervous system immune activation in HIV-1 infection.   AIDS Res Ther. 2010;7:15. doi:10.1186/1742-6405-7-15 PubMedGoogle ScholarCrossref
Gaetani  L , Höglund  K , Parnetti  L ,  et al.  A new enzyme-linked immunosorbent assay for neurofilament light in cerebrospinal fluid: analytical validation and clinical evaluation.   Alzheimers Res Ther. 2018;10(1):8. doi:10.1186/s13195-018-0339-1 PubMedGoogle ScholarCrossref
Yilmaz  A , Blennow  K , Hagberg  L ,  et al.  Neurofilament light chain protein as a marker of neuronal injury: review of its use in HIV-1 infection and reference values for HIV-negative controls.   Expert Rev Mol Diagn. 2017;17(8):761-770. doi:10.1080/14737159.2017.1341313 PubMedGoogle ScholarCrossref
Rosengren  LE , Ahlsén  G , Belfrage  M , Gillberg  C , Haglid  KG , Hamberger  A .  A sensitive ELISA for glial fibrillary acidic protein: application in CSF of children.   J Neurosci Methods. 1992;44(2-3):113-119. doi:10.1016/0165-0270(92)90004-W PubMedGoogle ScholarCrossref
Lee  MH , Perl  DP , Nair  G ,  et al.  Microvascular injury in the brains of patients with Covid-19.   N Engl J Med. 2021;384(5):481-483. doi:10.1056/NEJMc2033369PubMedGoogle ScholarCrossref
Matschke  J , Lütgehetmann  M , Hagel  C ,  et al.  Neuropathology of patients with COVID-19 in Germany: a post-mortem case series.   Lancet Neurol. 2020;19(11):919-929. doi:10.1016/S1474-4422(20)30308-2 PubMedGoogle ScholarCrossref
Remmelink  M , De Mendonça  R , D’Haene  N ,  et al.  Unspecific post-mortem findings despite multiorgan viral spread in COVID-19 patients.   Crit Care. 2020;24(1):495. doi:10.1186/s13054-020-03218-5 PubMedGoogle ScholarCrossref
Schurink  B , Roos  E , Radonic  T ,  et al.  Viral presence and immunopathology in patients with lethal COVID-19: a prospective autopsy cohort study.   Lancet Microbe. 2020;1(7):e290-e299. doi:10.1016/S2666-5247(20)30144-0 PubMedGoogle ScholarCrossref
Solomon  IH , Normandin  E , Bhattacharyya  S ,  et al.  Neuropathological features of Covid-19.   N Engl J Med. 2020;383(10):989-992. doi:10.1056/NEJMc2019373 PubMedGoogle ScholarCrossref
Remsik  J , Wilcox  JA , Babady  NE ,  et al.  Inflammatory leptomeningeal cytokines mediate COVID-19 neurologic symptoms in cancer patients.   Cancer Cell. 2021;39(2):276-283.e3. doi:10.1016/j.ccell.2021.01.007 PubMedGoogle ScholarCrossref
Varga  Z , Flammer  AJ , Steiger  P ,  et al.  Endothelial cell infection and endotheliitis in COVID-19.   Lancet. 2020;395(10234):1417-1418. doi:10.1016/S0140-6736(20)30937-5 PubMedGoogle ScholarCrossref
McCracken  IR , Saginc  G , He  L ,  et al.  Lack of evidence of angiotensin-converting enzyme 2 expression and replicative infection by SARS-CoV-2 in human endothelial cells.   Circulation. 2021;143(8):865-868. doi:10.1161/CIRCULATIONAHA.120.052824 PubMedGoogle ScholarCrossref
Bocci  M , Oudenaarden  C , Sàenz-Sardà  X ,  et al.  Infection of brain pericytes underlying neuropathology of COVID-19 patients.   Int J Mol Sci. 2021;22(21):11622. doi:10.3390/ijms222111622 PubMedGoogle ScholarCrossref
Mohammadhosayni  M , Sadat Mohammadi  F , Ezzatifar  F ,  et al.  Matrix metalloproteinases are involved in the development of neurological complications in patients with Coronavirus disease 2019.   Int Immunopharmacol. 2021;100:108076. doi:10.1016/j.intimp.2021.108076 PubMedGoogle ScholarCrossref
Bernard-Valnet  R , Perriot  S , Canales  M ,  et al.  Encephalopathies associated with severe COVID-19 present neurovascular unit alterations without evidence for strong neuroinflammation.   Neurol Neuroimmunol Neuroinflamm. 2021;8(5):e1029. doi:10.1212/NXI.0000000000001029 PubMedGoogle ScholarCrossref
Molero-Luis  M , Casas-Alba  D , Orellana  G ,  et al.  Cerebrospinal fluid neopterin as a biomarker of neuroinflammatory diseases.   Sci Rep. 2020;10(1):18291. doi:10.1038/s41598-020-75500-z PubMedGoogle ScholarCrossref
Heming  M , Li  X , Räuber  S ,  et al.  Neurological manifestations of COVID-19 feature T cell exhaustion and dedifferentiated monocytes in cerebrospinal fluid.   Immunity. 2021;54(1):164-175.e6. doi:10.1016/j.immuni.2020.12.011 PubMedGoogle ScholarCrossref
Song  E , Bartley  CM , Chow  RD ,  et al.  Divergent and self-reactive immune responses in the CNS of COVID-19 patients with neurological symptoms.   Cell Rep Med. 2021;2(5):100288. doi:10.1016/j.xcrm.2021.100288 PubMedGoogle ScholarCrossref
Gisslen  M , Keating  SM , Spudich  S ,  et al.  Compartmentalization of cerebrospinal fluid inflammation across the spectrum of untreated HIV-1 infection, central nervous system injury and viral suppression.   PLoS One. 2021;16(5):e0250987. doi:10.1371/journal.pone.0250987 PubMedGoogle ScholarCrossref
Remsik  J , Wilcox  JA , Babady  NE ,  et al.  Inflammatory leptomeningeal cytokines mediate delayed COVID-19 encephalopathy.   medRxiv. 2020. doi:10.1101/2020.09.15.20195511 Google Scholar
Kanberg  N , Simrén  J , Edén  A ,  et al.  Neurochemical signs of astrocytic and neuronal injury in acute COVID-19 normalizes during long-term follow-up.   EBioMedicine. 2021;70:103512. doi:10.1016/j.ebiom.2021.103512 PubMedGoogle ScholarCrossref
Westman  G , Aurelius  E , Ahlm  C ,  et al.  Cerebrospinal fluid biomarkers of brain injury, inflammation and synaptic autoimmunity predict long-term neurocognitive outcome in herpes simplex encephalitis.   Clin Microbiol Infect. 2021;27(8):1131-1136. doi:10.1016/j.cmi.2020.09.031 PubMedGoogle ScholarCrossref
Neumann  B , Schmidbauer  ML , Dimitriadis  K ,  et al; PANDEMIC and the IGNITE study groups.  Cerebrospinal fluid findings in COVID-19 patients with neurological symptoms.   J Neurol Sci. 2020;418:117090. doi:10.1016/j.jns.2020.117090PubMedGoogle ScholarCrossref
Venkatesan  A , Tunkel  AR , Bloch  KC ,  et al; International Encephalitis Consortium.  Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the International Encephalitis Consortium.   Clin Infect Dis. 2013;57(8):1114-1128. doi:10.1093/cid/cit458 PubMedGoogle ScholarCrossref
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