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. 2022 Apr 1;17(4):e0266184.
doi: 10.1371/journal.pone.0266184. eCollection 2022.

Validation of xMAP SARS-CoV-2 Multi-Antigen IgG assay in Nigeria

Nnaemeka C Iriemenam  1 , Fehintola A Ige  2 , Stacie M Greby  1 , Augustine Mpamugo  3 , Ado G Abubakar  4 , Ayuba B Dawurung  4 , Mudiaga K Esiekpe  4 , Andrew N Thomas  4 , Mary U Okoli  5 , Samuel S Awala  4 , Blessing N Ugboaja  4 , Chimaoge C Achugbu  5 , Ifeanyichukwu Odoh  4 , Felicia D Nwatu  4 , Temitope Olaleye  4 , Loveth Akayi  4 , Oluwaseun O Akinmulero  4 , Joseph Dattijo  4 , Edewede Onokevbagbe  3 , Olumide Okunoye  1 , Nwando Mba  5 , Ndidi P Agala  4 , Mabel Uwandu  2 , Maureen Aniedobe  2 , Kristen A Stafford  6 , Alash'le Abimiku  4   6 , Yohhei Hamada  7 , Mahesh Swaminathan  1 , McPaul I Okoye  1 , Laura C Steinhardt  8 , Rosemary Audu  2
Affiliations

Validation of xMAP SARS-CoV-2 Multi-Antigen IgG assay in Nigeria

Nnaemeka C Iriemenam et al. PLoS One. .

Abstract

Objective: There is a need for reliable serological assays to determine accurate estimates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence. Most single target antigen assays have shown some limitations in Africa. To assess the performance of a multi-antigen assay, we evaluated a commercially available SARS-CoV-2 Multi-Antigen IgG assay for human coronavirus disease 2019 (COVID-19) in Nigeria.

Methods: Validation of the xMAP SARS-CoV-2 Multi-Antigen IgG assay was carried out using well-characterized SARS-CoV-2 reverse transcription polymerase chain reactive positive (97) and pre-COVID-19 pandemic (86) plasma panels. Cross-reactivity was assessed using pre-COVID-19 pandemic plasma specimens (213) from the 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS).

Results: The overall sensitivity of the xMAP SARS-CoV-2 Multi-Antigen IgG assay was 75.3% [95% CI: 65.8%- 82.8%] and specificity was 99.0% [95% CI: 96.8%- 99.7%]. The sensitivity estimate increased to 83.3% [95% CI: 70.4%- 91.3%] for specimens >14 days post-confirmation of diagnosis. However, using the NAIIS pre-pandemic specimens, the false positivity rate was 1.4% (3/213).

Conclusions: Our results showed overall lower sensitivity and a comparable specificity with the manufacturer's validation. There appears to be less cross-reactivity with NAIIS pre-pandemic COVID-19 specimens using the xMAP SARS-CoV-2 Multi-Antigen IgG assay. In-country SARS-CoV-2 serology assay validation can help guide the best choice of assays in Africa.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Dot plot indicating logarithmic transformed MFI levels of antibody responses to SARS-CoV-2 IgG negative and positive specimens of the 2018 NAIIS pre-pandemic samples, Nigeria, 2021.
NCP = nucleocapsid, RBD = receptor-binding domain, S1 = spike.
See this image and copyright information in PMC

References

    1. WHO. Coronavirus disease 2019 (COVID-19) Situation Report– 94: https://www.who.int/docs/default-source/coronaviruse/situation-reports/2... 2020. [cited 2021 February 25]. Available from: https://www.who.int/docs/default-source/coronaviruse/situation-reports/2....
    1. WHO. WHO Coronavirus Disease (COVID-19) Dashboard https://covid19.who.int/2022 [cited 2022 January 17]. Available from: https://covid19.who.int/.
    1. WHO. Coronavirus disease (COVID-19) technical guidance: The Unity Studies: Early Investigation Protocols: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technica... 2020. [cited 2021 February 25]. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technica....
    1. FDA. EUA Authorized Serology Test Performance: https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-em... 2021. [cited 2021 March 1]. Available from: https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-em....
    1. WHO. Emergency use listing: https://www.who.int/teams/regulation-prequalification/eul; 2021. [cited 2021 March 9]. Available from: https://www.who.int/teams/regulation-prequalification/eul.

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