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. 2025 Jul 28:9:349.
doi: 10.12688/wellcomeopenres.20240.2. eCollection 2024.

Comparative performance of the InBios SCoV-2 Detect TM IgG ELISA and the in-house KWTRP ELISA in detecting SARS-CoV-2 spike IgG antibodies in Kenyan populations

Bernadette Kutima  1 , Eunice Wageci Kagucia  1 , Kennedy Mwai  1 , Makobu Kimani  1 , Antipa Sigilai  1 , Daisy Mugo  1 , Henry Karanja  1 , John N Gitonga  1 , Angela Karani  1 , Donald Akech  1 , Monica Toroitich  1 , Boniface Karia  1 , James Tuju  1 , Abdhalah K Ziraba  2 , Godfrey Bigogo  3 , Caroline Ochieng  4 , Clayton Onyango  3 , Shirley Lidechi  3 , Patrick K Munywoki  5 , Sophie Uyoga  1 , Ifedayo M O Adetifa  1   6 , Lynette I Ochola Oyier  1 , Philip Bejon  1   7 , J Anthony G Scott  1   6 , Ambrose Agweyu  1   6 , George M Warimwe  1   7 , James Nyagwange  1 ; Kenya SARS-CoV-2 Serology Consortium
Affiliations

Comparative performance of the InBios SCoV-2 Detect TM IgG ELISA and the in-house KWTRP ELISA in detecting SARS-CoV-2 spike IgG antibodies in Kenyan populations

Bernadette Kutima et al. Wellcome Open Res. .

Abstract

Background: The InBios SCoV-2 Detect™ IgG ELISA (InBios) and the in-house KWTRP ELISA (KWTRP) have both been used in the estimation of SARS-CoV-2 seroprevalence in Kenya. Whereas the latter has been validated extensively using local samples, the former has not. Such validation is important for informing the comparability of data across the sites and populations where seroprevalence has been reported.

Methods: We compared the assays directly using pre-pandemic serum/plasma collected in 2018 from 454 blood donors and 173 malaria cross-sectional survey participants, designated gold standard negatives. As gold standard SARS-CoV-2 positive samples: we assayed serum/plasma from 159 SARS-CoV-2 PCR-positive patients and 166 vaccination-confirmed participants.

Results: The overall agreement on correctly classified samples was >0.87 for both assays. The overall specificity was 0.89 (95% CI, 0.87-0.91) for InBios and 0.99 (95% CI, 0.97-0.99) for KWTRP among the gold standard negative samples while the overall sensitivity was 0.97 (95% CI, 0.94-0.98) and 0.93 (95% CI, 0.90- 0.95) for InBios and KWTRP ELISAs respectively, among the gold standard positive samples. In all, the positive predictive value for InBios was 0.83 (95% CI, 0.79-0.87) and 0.98 (95% CI, 0.96-0.99) for KWTRP while the negative predictive value was 0.98 (95% CI, 0.97- 0.99) and 0.97 (95% CI, 0.95-0.98) for InBios and KWTRP respectively.

Conclusions: Overall, both assays showed sufficient sensitivity and specificity to estimate SARS-CoV-2 antibodies in different populations in Kenya.

Keywords: IgG; Immunoassay; SARS-CoV-2; Serology; Total immunoglobulin.

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Conflict of interest statement

No competing interests were disclosed.

Figures

Figure 1.
Figure 1.. Relationship between antibody response and duration since vaccination.
Each point represents one of the 166 vaccination-confirmed individuals included in the gold standard positive panel. The Immune Status Ratio (ISR) for InBios ( A) and Optical Density Ratio for KWTRP ( B) are shown for the duration between the day of vaccination and the sampling date of the serum/plasma used in the ELISAs.
Figure 2.
Figure 2.. ROC curves for InBios and KWTRP ELISAs using the OD ratios of all the gold standard positives and negatives as assay population.
Figure 3.
Figure 3.
Inter-assay variation of InBios ( A) and KWTRP ( B) ELISAs by assessing the raw ODs of the negative, positive, and cut-off controls for all the runs done during the comparison.
See this image and copyright information in PMC

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