Epistatic models predict mutable sites in SARS-CoV-2 proteins and epitopes

TL;DR

This study develops epistatic models to predict mutability in SARS-CoV-2 proteins, enabling anticipation of future variants and informing vaccine and therapeutic strategies.

Contribution

The paper introduces statistical models based on epistasis that outperform conservation profiles in predicting SARS-CoV-2 mutability and variant emergence.

Findings

Models predict mutability correlates with experimental stability measures.

Predictions improve with more data over time, showing anticipatory capacity.

Identifies mutation-prone sites linked to variants of concern.

Abstract

The emergence of new variants of SARS-CoV-2 is a major concern given their potential impact on the transmissibility and pathogenicity of the virus as well as the efficacy of therapeutic interventions. Here, we predict the mutability of all positions in SARS-CoV-2 protein domains to forecast the appearance of unseen variants. Using sequence data from other coronaviruses, pre-existing to SARS-CoV-2, we build statistical models that do not only capture amino-acid conservation but more complex patterns resulting from epistasis. We show that these models are notably superior to conservation profiles in estimating the already observable SARS-CoV-2 variability. In the receptor binding domain of the spike protein, we observe that the predicted mutability correlates well with experimental measures of protein stability and that both are reliable mutability predictors (ROC AUC ~0.8). Most interestingly, we observe an increasing agreement between our model and the observed variability as more data become available over time, proving the anticipatory capacity of our model. When combined with data concerning the immune response, our approach identifies positions where current variants of concern are highly overrepresented. These results could assist studies on viral evolution, future viral outbreaks and, in particular, guide the exploration and anticipation of potentially harmful future SARS-CoV-2 variants.