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Volume 30, Number 3—March 2024
Dispatch

Biphasic MERS-CoV Incidence in Nomadic Dromedaries with Putative Transmission to Humans, Kenya, 2022–2023

Brian Maina Ogoti1, Victor Riitho1, Johanna Wildemann1, Nyamai Mutono, Julia Tesch, Jordi Rodon, Kaneemozhe Harichandran, Jackson Emanuel, Elisabeth Möncke-Buchner, Stella Kiambi, Julius Oyugi, Marianne Mureithi, Victor M. Corman, Christian Drosten, Samuel M. Thumbi1, and Marcel A. Müller1Comments to Author 
Author affiliations: University of Nairobi, Nairobi, Kenya (B.M. Ogoti, V. Riitho, N. Mutono, J. Oyugi, M. Mureithi, S.M. Thumbi); Queen Mary University of London, London, UK (V. Riitho); Charité–Universitätsmedizin Berlin, Berlin, Germany (J. Wildemann, J. Tesch, J. Rodon, K. Harichandran, J. Emanuel, E. Möncke-Buchner, V.M. Corman, C. Drosten, M.A. Müller); Washington State University, Pullman, Washington, USA (N. Mutono, S.M. Thumbi); Food and Agriculture Organization, Dar es Salaam, Tanzania (S. Kiambi); Labor Berlin–Charité Vivantes GmbH, Berlin (V.M. Corman); German Center for Infection Research, Berlin (V.M. Corman, C. Drosten, M.A. Müller); University of Edinburgh, Edinburgh, Scotland, UK (S.M. Thumbi)

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Figure 2

MERS-CoV immune responses in camel-exposed abattoir workers in Isiolo, Kenya. A) Results of commercial MERS-CoV S1-protein ELISA to detect IgG responses in 48 serum samples (diluted 1:100) from Isiolo abattoir workers. Samples with ODR >0.2 were considered ELISA-reactive, suggesting that 7/48 persons had MERS-CoV–reactive IgGs. Of note, all persons tested negative by MERS-CoV quantitative reverse transcription PCR. B) GFP-VSVpp-MERS-CoV S protein-based neutralization test (VSVpp-NT). VSVpp-S (EMC) and VSVpp-S (Kenya) contained human codon-optimized Spikes from prototypic MERS-CoV EMC/2012 clade A and Kenya clade C2.2 (#L00009980). All 7 ELISA-reactive human serum samples were mixed with 200 foci-forming units VSVpp in final serum dilutions 1:20–1:160. Out of the 7 ELISA-reactive persons, 1 showed a VSVpp-NT 50% foci-forming units reduction titer of 1:20 (EMC) and 1:40 (Kenya). The picture shows an example of the 1:20 dilution of an ELISA-reactive (#11717) and ELISA-nonreactive (#11738) abattoir worker. Negative control = ELISA-negative human serum (1:20) was used as reference and set to 100%. Positive control = monoclonal anti-MERS-CoV Spike receptor-binding domain binding antibody (mAb 7.7G6) previously shown to neutralize MERS-CoV at the tested dilution (1:2 × 105). For better graphical visibility, all pictures were enhanced in contrast and brightness identically. mAb, monoclonal antibody; MERS-CoV, Middle East respiratory syndrome coronavirus; ODR, optical density ratio; VSVpp, vesicular stomatitis virus pseudoparticles.

Figure 2. MERS-CoV immune responses in camel-exposed abattoir workers in Isiolo, Kenya. A) Results of commercial MERS-CoV S1-protein ELISA to detect IgG responses in 48 serum samples (diluted 1:100) from Isiolo abattoir workers. Samples with ODR >0.2 were considered ELISA-reactive, suggesting that 7/48 persons had MERS-CoV–reactive IgGs. Of note, all persons tested negative by MERS-CoV quantitative reverse transcription PCR. B) GFP-VSVpp-MERS-CoV S protein-based neutralization test (VSVpp-NT). VSVpp-S (EMC) and VSVpp-S (Kenya) contained human codon-optimized Spikes from prototypic MERS-CoV EMC/2012 clade A and Kenya clade C2.2 (#L00009980). All 7 ELISA-reactive human serum samples were mixed with 200 foci-forming units VSVpp in final serum dilutions 1:20–1:160. Out of the 7 ELISA-reactive persons, 1 showed a VSVpp-NT 50% foci-forming units reduction titer of 1:20 (EMC) and 1:40 (Kenya). The picture shows an example of the 1:20 dilution of an ELISA-reactive (#11717) and ELISA-nonreactive (#11738) abattoir worker. Negative control = ELISA-negative human serum (1:20) was used as reference and set to 100%. Positive control = monoclonal anti-MERS-CoV Spike receptor-binding domain binding antibody (mAb 7.7G6) previously shown to neutralize MERS-CoV at the tested dilution (1:2 × 105). For better graphical visibility, all pictures were enhanced in contrast and brightness identically. mAb, monoclonal antibody; MERS-CoV, Middle East respiratory syndrome coronavirus; ODR, optical density ratio; VSVpp, vesicular stomatitis virus pseudoparticles.

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1These authors contributed equally to this article.

Page created: January 15, 2024
Page updated: February 22, 2024
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