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Background <p>The reported number of SARS-CoV-2 cases and deaths are lower in Africa compared to many high-income countries. However, in African cohorts, detailed characterisation of SARS-CoV-2 mucosal and T cell immunity are limited. We assessed the SARS-CoV-2-specific immune landscape in The Gambia during the presence of the pre-Delta variant in July 2021.</p> Methods <p>A cross-sectional assessment of SARS-CoV-2 immunity in 349 unvaccinated individuals from 52 Gambian households was performed between March–June 2021. SARS-CoV-2 spike (S) and nucleocapsid (N) specific binding antibodies were measured by ELISA, variant-specific serum neutralizing-antibodies (NAb) by viral pseudotype assays and nasal fluid IgA by mesoscale discovery assay. SARS-CoV-2 T-cell responses were evaluated using ELISpot assay.</p> Results <p>We show that adjusted anti-Spike antibody seroprevalence is 56.7% (95% confidence interval (CI) 49.0-64.0), with lower rates in children &lt;5 years (26.2%, 13.9-43.8) and 5-17 years (46.4%, 36.2-56.7) compared to adults 18-49 years (78.4%, 68.8–85.8). Among spike-seropositive individuals, NAb titres are highest against Alpha variant (median IC50 110), with 27% showing pre-existing Delta variant titres &gt;1:50. T-cell responses are higher in spike-seropositive individuals, although 34% of spike-seronegative individuals show responses to at least one antigen pool. We observe strong correlations within SARS-CoV-2 T-cell, mucosal IgA, and serum NAb responses.</p> Conclusions <p>High SARS-CoV-2 seroprevalence in The-Gambia induce mucosal and blood immunity, reducing Delta and Omicron impact. Children are relatively protected from infection. T-cell responses in seronegative individuals may indicate either pre-pandemic cross-reactivity or individuals with a T-cell dominated response to SARS-CoV-2 infection with absent or poor humoral responses.</p>

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Compartmentalised mucosal and blood immunity to SARS-CoV-2 is associated with high seroprevalence before the Delta wave in Africa

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年5月16日

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  • Ya Jankey Jagne,
  • Dawda Jobe,
  • Alansana Darboe,
  • Madikoi Danso,
  • Natalie Barratt,
  • Marie Gomez,
  • Rhys Wenlock,
  • Sheikh Jarju,
  • Ellen Lena Sylva,
  • Aji Fatou Touray,
  • Fatoumata Toure,
  • Michelle Kumado,
  • Anja Saso,
  • Domen Zafred,
  • Martin Nicklin,
  • Jon Sayers,
  • Hailey Hornsby,
  • Benjamin Lindsey,
  • Abdul Karim Sesay,
  • Nigel Temperton,
  • Adam Kucharski,
  • David Hodgson,
  • Thushan de Silva,
  • Beate Kampmann

摘要

Background

The reported number of SARS-CoV-2 cases and deaths are lower in Africa compared to many high-income countries. However, in African cohorts, detailed characterisation of SARS-CoV-2 mucosal and T cell immunity are limited. We assessed the SARS-CoV-2-specific immune landscape in The Gambia during the presence of the pre-Delta variant in July 2021.

Methods

A cross-sectional assessment of SARS-CoV-2 immunity in 349 unvaccinated individuals from 52 Gambian households was performed between March–June 2021. SARS-CoV-2 spike (S) and nucleocapsid (N) specific binding antibodies were measured by ELISA, variant-specific serum neutralizing-antibodies (NAb) by viral pseudotype assays and nasal fluid IgA by mesoscale discovery assay. SARS-CoV-2 T-cell responses were evaluated using ELISpot assay.

Results

We show that adjusted anti-Spike antibody seroprevalence is 56.7% (95% confidence interval (CI) 49.0-64.0), with lower rates in children <5 years (26.2%, 13.9-43.8) and 5-17 years (46.4%, 36.2-56.7) compared to adults 18-49 years (78.4%, 68.8–85.8). Among spike-seropositive individuals, NAb titres are highest against Alpha variant (median IC50 110), with 27% showing pre-existing Delta variant titres >1:50. T-cell responses are higher in spike-seropositive individuals, although 34% of spike-seronegative individuals show responses to at least one antigen pool. We observe strong correlations within SARS-CoV-2 T-cell, mucosal IgA, and serum NAb responses.

Conclusions

High SARS-CoV-2 seroprevalence in The-Gambia induce mucosal and blood immunity, reducing Delta and Omicron impact. Children are relatively protected from infection. T-cell responses in seronegative individuals may indicate either pre-pandemic cross-reactivity or individuals with a T-cell dominated response to SARS-CoV-2 infection with absent or poor humoral responses.