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A Founder Effect Led Early SARS-CoV-2 Transmission in Spain
Francisco Díez-Fuertes1,2, María Iglesias-Caballero3, Javier García-Pérez4
1AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain frdiez@clinic.cat icasas@isciii.es.
Journal of Virology
|October 31, 2020
Summary
Multiple SARS-CoV-2 introductions into Spain led to local clusters, with early variants showing a founder effect. Later, G614 viruses with enhanced infectivity replaced D614 variants, driving the epidemic
Area of Science:
- Virology
- Epidemiology
- Genomics
Background:
- Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread globally, with distinct clades identified.
- Understanding viral diffusion patterns and genetic evolution is crucial for pandemic response.
Purpose of the Study:
- To analyze the introduction and phylogenetic diffusion of SARS-CoV-2 within Spain.
- To investigate the emergence of specific SARS-CoV-2 clades and their evolutionary dynamics in Spain.
Main Methods:
- Maximum-likelihood phylogenetic analysis of SARS-CoV-2 whole-genome sequences.
- Bayesian phylodynamic analyses to estimate the most recent common ancestor (MRCA).
- Analysis of sequence data from Spain in the context of global SARS-CoV-2 clades.
Main Results:
- Spain experienced 62 independent introductions of SARS-CoV-2.
- Early introductions were dominated by clade 19B (D614 variant), suggesting a founder effect.
- Clades 20A, 20B, and 20C (G614 variant) with enhanced infectivity eventually predominated, replacing D614 variants.
Conclusions:
- At least four SARS-CoV-2 introductions resulted in significant local transmission clusters in Spain.
- The shift from D614 to G614 variants in Spain was likely driven by the G614 substitution's fitness advantage.
- These findings highlight the importance of genomic surveillance for understanding viral evolution and spread.
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