Hénaut M, Carbonneau J, Rhéaume C, Levade I, Boivin G. In vitro fitness of SARS-CoV-2 variants as assessed by competition experiments followed by ddRT-PCR and whole genome sequencing.
J Clin Virol 2023;
165:105517. [PMID:
37321149 DOI:
10.1016/j.jcv.2023.105517]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/05/2023] [Accepted: 06/05/2023] [Indexed: 06/17/2023]
Abstract
OBJECTIVE
To develop a new method for reliable and rapid determination of the fitness of SARS-CoV-2 variants of concern.
METHODS
Competition experiments between two SARS-CoV-2 variants were performed in cells of the upper (nasal human airway epithelium) and lower (Calu-3 cells) respiratory tracts followed by quantification of variant ratios by droplet digital reverse transcription (ddRT)-PCR.
RESULTS
In competition experiments, the delta variant outcompeted the alpha variant in both cells of the upper and lower respiratory tracts. A 50/50% mixture of delta and omicron variants indicated a predominance of omicron in the upper respiratory tract whereas delta predominated in the lower respiratory tract. There was no evidence of recombination events between variants in competition as assessed by whole gene sequencing.
CONCLUSION
Differential replication kinetics were shown between variants of concern which may explain, at least partly, the emergence and disease severity associated with new SARS-CoV-2 variants.
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