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Amino acid substitution L232F in non-structural protein 6 identified as a possible human-adaptive mutation in clade B MERS coronaviruses

Abstract:
Middle East respiratory syndrome coronavirus (MERS-CoV) causes zoonotic disease. Dromedary camels are the source of zoonotic infection. We performed sequence analysis of clade B MERS-CoV after excluding potential bias arising multiple sequences from a single zoonotic transmission chain and identified a substitution of amino acid leucine to phenylalanine in the codon 232 position of the non-structural protein 6 (nsp6) (nsp6 L232F) that occurs preferentially in human clade B MERS-CoV, with a rate of 16.9% (20/118) in human sequences vs a 0.6% (1/160) in camel sequences. Using a human clade B MERS-CoV strain GD01 as backbone, we generated a pair of isogenic recombinant MERS-CoV with nsp6 232L and 232F residues, respectively, and showed that the nsp6 L232F substitution confers higher replication competence in ex vivo culture of human nasal and bronchial tissues and in lungs of mice experimentally infected in vivo. Mechanistically, the nsp6 L232F substitution was found to associate with higher exocytic virus egress, while innate immune responses, autophagic restriction, and zippering activity of the endoplasmic reticulum remained unaffected. Our study suggests an adaptive mutation that occurs in clade B MERS-CoV associated with inter-species transmission to humans that may facilitate higher viral replication in the human respiratory tract. This highlights the importance of MERS-CoV as a zoonotic threat and the need for continued virus surveillance in camels and humans.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1128/jvi.01369-23

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Role:
Author
ORCID:
0000-0002-9576-4489
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Role:
Author
ORCID:
0000-0002-0525-6772


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Funder identifier:
https://ror.org/029chgv08
Grant:
220776/Z/20/Z
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Funder identifier:
https://ror.org/045p44t13
Grant:
U01-Grant AI151810
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Funder identifier:
https://ror.org/00cwqg982
Grant:
BB/Y000307/1


Publisher:
American Society for Microbiology
Journal:
Journal of Virology More from this journal
Volume:
97
Issue:
12
Article number:
e0136923
Place of publication:
United States
Publication date:
2023-12-01
Acceptance date:
2023-11-09
DOI:
EISSN:
1098-5514
ISSN:
0022-538X
Pmid:
38038429


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