SARS-CoV-2 antigens expressed in plants detect antibody responses in COVID-19 patients

Abstract Background The SARS-CoV-2 pandemic has swept the world and poses a significant global threat to lives and livelihoods, with over 16 million confirmed cases and at least 650 000 deaths from COVID-19 in the first 7 months of the pandemic. Developing tools to measure seroprevalence and understand protective immunity to SARS-CoV-2 is a priority. We aimed to develop a serological assay using plant-derived recombinant viral proteins, which represent important tools in less-resourced settings.Methods We established an indirect enzyme-linked immunosorbent assay (ELISA) using the S1 and receptor-binding domain (RBD) portions of the spike protein from SARS-CoV-2, expressed in Nicotiana benthamiana. We measured antibody responses in sera from South African patients (n=77) who had tested positive by PCR for SARS-CoV-2. Samples were taken a median of six weeks after the diagnosis, and the majority of participants had mild and moderate COVID-19 disease. In addition, we tested the reactivity of pre-pandemic plasma (n=58) and compared the performance of our in-house ELISA with a commercial assay. We also determined whether our assay could detect SARS-CoV-2-specific IgG and IgA in saliva.Results We demonstrate that SARS-CoV-2-specific immunoglobulins are readily detectable using recombinant plant-derived viral proteins, in patients who tested positive for SARS-CoV-2 by PCR. Reactivity to S1 and RBD was detected in 51 (66%) and 48 (62%) of participants, respectively. Notably, we detected 100% of samples identified as having S1-specific antibodies by a validated, high sensitivity commercial ELISA, and OD values were strongly and significantly correlated between the two assays. For the pre-pandemic plasma, 1/58 (1.7%) of samples were positive, indicating a high specificity for SARS-CoV-2 in our ELISA. SARS-CoV-2-specific IgG correlated significantly with IgA and IgM responses. Endpoint titers of S1- and RBD-specific immunoglobulins ranged from 1:50 to 1:3200. S1-specific IgG and IgA were found in saliva samples from convalescent volunteers.Conclusions We demonstrate that recombinant SARS-CoV-2 proteins produced in plants enable robust detection of SARS-CoV-2 humoral responses. This assay can be used for seroepidemiological studies and to measure the strength and durability of antibody responses to SARS-CoV-2 in infected patients in our setting..

Medienart:

Preprint

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

bioRxiv.org - (2021) vom: 15. Dez. Zur Gesamtaufnahme - year:2021

Sprache:

Englisch

Beteiligte Personen:

Makatsa, Mohau S. [VerfasserIn]
Tincho, Marius B. [VerfasserIn]
Wendoh, Jerome M. [VerfasserIn]
Ismail, Sherazaan D. [VerfasserIn]
Nesamari, Rofhiwa [VerfasserIn]
Pera, Francisco [VerfasserIn]
Beer, Scott de [VerfasserIn]
David, Anura [VerfasserIn]
Jugwanth, Sarika [VerfasserIn]
Gededzha, Maemu P. [VerfasserIn]
Mampeule, Nakampe [VerfasserIn]
Sanne, Ian [VerfasserIn]
Stevens, Wendy [VerfasserIn]
Scott, Lesley [VerfasserIn]
Blackburn, Jonathan [VerfasserIn]
Mayne, Elizabeth S. [VerfasserIn]
Keeton, Roanne S. [VerfasserIn]
Burgers, Wendy A. [VerfasserIn]

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doi:

10.1101/2020.08.04.20167940

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

XBI018503543