Oxford University Press Study Reveals SARS-CoV-2 Evolution Is Tightly Constrained by Spike Protein Structural Stability

A new study finds that COVID-19 variants emerge through combinations of existing mutations, limited by the structural stability of the spike protein.

By: AXL Media

Published: Mar 25, 2026, 5:24 AM EDT

Source: Information for this report was sourced from Oxford University Press USA

The Paradox of Rapid but Constrained Evolution

Since its emergence in late 2019, the SARS-CoV-2 virus has been characterized by a perceived ability to undergo dramatic and unpredictable changes. However, a new study led by researchers at the University of Glasgow and published by Oxford University Press suggests that this evolution is far more restricted than previously feared. By analyzing massive global genomic datasets, investigators found that while the virus has diversified, it has done so within very specific and unchanging genetic boundaries. This discovery challenges the earlier scientific assumption that the virus was constantly unlocking entirely new evolutionary pathways to increase its strength or transmissibility in human hosts.

The Role of Structural Constraint in Variant Emergence

The focus of the investigation was the spike protein, the crown-like structure that allows the virus to latch onto human cells. Many scientists initially believed that as the virus evolved into new variants, the spike protein’s structure was shifting in ways that enabled previously impossible mutations. However, the researchers utilized protein structural determination and computational predictors to find that the "structural constraint" of the spike protein has remained remarkably stable. Despite strong selective pressure and high mutation rates, the virus is physically limited by the need to maintain a stable spike protein, preventing it from exploring a wider range of genetic possibilities.

A Shift From New Mutations to Novel Combinations

The research team identified several distinct phases of the pandemic’s progression, beginning with a period of neutral diversification that lasted until late 2020. Following this, multi-mutant variants began to emerge, often designated by the World Health Organization as variants of concern due to increased immune escape or transmissibility. The study clarifies that these successful variants did not arise because the virus became more flexible. Instead, the virus achieved "success" by creating novel combinations of mutations that already existed within its viable genetic space. This functional interaction between known mutations allowed the virus to adapt without breaking its structural limits.