PLoS ONE (Jan 2022)

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

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

DOI
https://doi.org/10.1371/journal.pone.0266184
Journal volume & issue
Vol. 17, no. 4
p. e0266184

Abstract

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ObjectiveThere 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.MethodsValidation 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).ResultsThe 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).ConclusionsOur 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.