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Production of a SARS-CoV-2 Virus-Like-Particle System to Investigate Viral Life Cycles In Vitro
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SARS-CoV-2 variants reveal features critical for replication in primary human cells
Marie O Pohl1, Idoia Busnadiego1, Verena Kufner1
1Institute of Medical Virology, University of Zurich, Zurich, Switzerland.
Plos Biology
|March 24, 2021
Summary
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants show cell-specific replication differences. Understanding these SARS-CoV-2 genetic changes is crucial for monitoring virus evolution and potential variants of concern.
Area of Science:
- Virology
- Genetics
- Cell Biology
Background:
- Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused a global pandemic.
- Numerous genetic variants have emerged, but their impact on viral properties is not fully understood.
- Characterizing these variants is essential for understanding virus adaptation and transmission.
Purpose of the Study:
- To investigate the impact of naturally occurring SARS-CoV-2 variants on viral replication in different cell types.
- To identify specific genetic features associated with distinct viral phenotypes.
- To assess the influence of cell culture conditions on variant selection and viral fitness.
Main Methods:
- Characterization of 14 low-passage, replication-competent SARS-CoV-2 isolates from early 2020 European clades.
- Integration of viral sequencing data from patient samples, virus stocks, and passaging experiments.
- Kinetic virus replication assays in Vero-CCL81 cells and primary human bronchial epithelial cells (BEpCs).
Main Results:
- Naturally occurring Orf3a (Q57H) and nsp2 (T85I) variants showed poor replication in Vero-CCL81 cells but not BEpCs.
- The Spike D614G variant was associated with enhanced replication in BEpCs.
- Vero cell passage selected for E protein substitutions, leading to attenuation in BEpCs.
- Deletions in the Spike furin cleavage site during Vero passage were detrimental to replication in BEpCs.
Conclusions:
- SARS-CoV-2 sequence features determine cell-specific replication phenotypes.
- The Spike furin cleavage site is critical for SARS-CoV-2 replication in primary human cells.
- Careful monitoring of SARS-CoV-2 stocks is necessary when phenotyping new variants or variants of concern.
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