Deep Learning-Driven Prediction of Viral Receptor-Binding Domain Evolution and Escape Mutations

Introduction

The receptor-binding domain (RBD) of viral glycoproteins is a primary determinant of host cell tropism and a major target of neutralizing antibodies. In RNA viruses, the high mutation rate of the RNA-dependent [RNA polymerase](/knowledge/bioinformatics/rna-polymerase-structure-transcription-mechanisms 2) generates extensive sequence diversity that enables the RBD to escape antibody recognition while maintaining or increasing binding affinity to the host receptor [1, 2, 3]. This evolutionary arms race presents a critical challenge for veterinary vaccine design and diagnostic surveillance. Traditional experimental approaches, such as deep mutational scanning and neutralization assays, are resource-intensive and cannot keep pace with the rapid emergence of variants [4, 5, 6]. Deep learning models, including protein language models (e.g., ESM-1b) and structure prediction networks (e.g., AlphaFold2), have emerged as powerful tools to predict RBD evolution and identify escape mutations before they dominate viral populations [7, 8]. This article reviews the computational biology frameworks that enable sequence-to-structure mapping, binding affinity prediction, and generative design of immune escape variants, with a focus on viral pathogens relevant to veterinary medicine. Emphasis is placed on the biophysical mechanisms of RBD-receptor interactions and the algorithmic foundations of the predictive models.

Sequence-to-Structure Mapping of RBDs

The accurate prediction of three-dimensional RBD structures from amino acid sequences is a prerequisite for understanding mutation-induced conformational changes. AlphaFold2, a deep learning architecture based on attention mechanisms and geometric constraints, has achieved near-experimental accuracy for many viral glycoproteins [9, 10, 11]. By leveraging co-evolutionary information from multiple sequence alignments and structural templates, AlphaFold2 predicts the spatial arrangement of RBD residues with root-mean-square deviations typically less than 2 Å for core regions [12, 13]. In the context of veterinary coronaviruses, AlphaFold2 has been used to model the RBDs of bat, feline, and canine coronaviruses, revealing key structural features that govern cross-species receptor binding [14, 15].

Protein language models such as ESM-1b provide an alternative approach by learning distributed representations of amino acid sequences through masked language modeling. These embeddings capture evolutionary and biophysical properties without requiring co-evolutionary data, making them particularly useful for viruses with limited sequence sampling [16, 17, 18]. ESM-1b has been applied to predict the fitness effects of individual missense mutations in the influenza hemagglutinin (HA) RBD, demonstrating that the model can prioritize residues under strong positive selection [19, 20]. When combined with Rosetta-based energy functions, these embeddings can be projected onto predicted structures to identify clusters of mutations that destabilize antibody epitopes while retaining receptor binding [21, 22, 23].

Binding Affinity Prediction and Host Range Shifts

The binding affinity between the viral RBD and the host receptor is a quantitative measure of entry efficiency and a major determinant of host range. Deep learning models that integrate structural and sequence features have been trained on large-scale experimental binding data to predict the change in Gibbs free energy (ΔΔG) upon mutation [24, 25, 26]. Graph neural networks operating on residue contact maps can capture long-range epistatic interactions that are missed by linear sequence models [27, 28, 29]. For example, mutations in the angiotensin-converting enzyme 2 (ACE2) binding interface of SARS-CoV-2 RBD, such as N501Y and L455S, have been systematically evaluated using these models, and the predicted ΔΔG values correlate well with experimental surface plasmon resonance measurements and pseudovirus entry assays [19, 24, 30].

In veterinary influenza, the binding specificity of HA for α2,3-linked sialic acids (avian receptors) versus α2,6-linked sialic acids (mammalian receptors) is a hallmark of host range adaptation. Deep learning classifiers trained on HA sequences from avian, swine, and equine isolates can predict receptor binding preference with over 90% accuracy [16, 17]. These models rely on convolutional neural networks that scan the HA1 domain for known signature motifs. The predicted binding specificity can be mapped onto a phylogenetic tree to identify branches with enhanced zoonotic potential [13, 31, 3].

Generative Design of Escape Variants

Beyond prediction, deep generative models can propose novel RBD sequences that are likely to evade current immunity. Variational autoencoders (VAEs) and generative adversarial networks (GANs) trained on viral sequence databases can sample the fitness landscape and output mutants that maximize antibody escape while minimizing receptor binding loss [4, 6, 7]. These in silico designs serve as hypotheses for subsequent experimental validation via neutralization assays. In a recent proof-of-concept, a generative model trained on SARS-CoV-2 Omicron sublineage sequences identified the F486S and R346T mutations as high-probability escape candidates, which were later confirmed in clinical isolates [5, 32, 8].

Similarly, for influenza A virus (subtype H3N2), a protein language model conditioned on the HA subclade K sequence generated a panel of RBD variants that reduced neutralization by ferret antisera raised against the 2025 vaccine strain [16, 17]. The generative approach accelerates the surveillance pipeline by providing a ranked list of mutations to monitor in next-generation sequencing data.

Real-World Examples in Veterinary Virology

SARS-CoV-2 in Companion and Farm Animals

SARS-CoV-2 has demonstrated the ability to infect domestic cats, dogs, mink, and white-tailed deer, leading to sustained transmission and RBD evolution within these hosts [1, 13, 27]. Deep mutational scanning of the RBD in a pseudovirus system revealed that the mutations Q493R and P681H, which were enriched in mink-associated variants, confer increased binding to cat ACE2 while partially escaping polyclonal antibodies from vaccinated humans [19, 5, 12]. Deep learning models trained on the entire known RBD mutational landscape predicted that the triple mutant L455S+F456L+Q493R would emerge under strong antibody pressure, a prediction later corroborated by clinical surveillance in canines [24, 28, 15].

Influenza Hemagglutinin in Swine and Poultry

Swine influenza H1N1 and H3N2 viruses are a constant threat due to their ability to generate antigenically novel strains through reassortment. The emergence of the H3N2 subclade K in 2025, which harbors a unique set of HA RBD mutations, was retrospectively predictable using a convolutional neural network that analyzed epitope conservation scores [16, 17]. The model highlighted reduced cross-conservation of T cell epitopes in the HA head domain, explaining the observed vaccine breakthrough in pigs [21, 22]. Poultry influenza H5N1 highly pathogenic avian influenza (HPAI) RBD mutations that shift receptor binding from avian to human-like sialic acids have been identified through structure-based deep learning docking of HA with receptor analogs [6, 2, 11].

Workflow for Integration Deep Learning in RBD Surveillance

The following Mermaid diagram illustrates a typical computational pipeline that integrates deep learning with experimental validation to predict and preempt immune escape mutations.

flowchart TD
    A[Viral sequence database<br/>GISAID, NCBI, IRD], > B[Multiple sequence alignment<br/>MAFFT, HMMER]
    B, > C{Deep Learning<br/>Model}
    C, > D[Structure prediction<br/>AlphaFold2, ESMFold]
    C, > E[Binding affinity prediction<br/>Graph neural network]
    C, > F[Generative escape design<br/>VAE, GAN]
    D, > G[ΔΔG calculation<br/>Rosetta, FoldX]
    E, > G
    F, > H[Ranked mutation list]
    G, > H
    H, > I[Experimental validation<br/>Pseudovirus assay, SPR]
    I, > J[Surveillance update<br/>Primer design, variant calling]
    J, > A

The pipeline begins with curated sequence databases. Deep learning models map sequences to structures and predict binding energies. Generative models propose novel escape variants. Only the top-ranked candidates enter experimental validation. Validated mutations update surveillance primers and inform vaccine strain selection.

Future Directions

Future developments will focus on multi-modal models that integrate genomic, structural, and serological data to predict the evolutionary trajectory of RBDs in near real time [9, 18, 7]. Attention-based architectures that can process whole spike trimer assemblies (including glycans) will improve the accuracy of epitope masking predictions [10, 23]. In veterinary settings, the application of these models to less-studied pathogens such as feline coronavirus (FCoV), canine respiratory coronavirus, and equine influenza remains an area of active research [25, 31, 14].

For a complementary discussion on AlphaFold-based viral structure prediction, see AlphaFold and Beyond: Deep Learning for Protein Structure Prediction in Veterinary Virology. The computational design of pan-vaccines targeting conserved RBD epitopes is covered in Machine Learning-Guided Design of Pan-Coronavirus Spike Protein Inhibitors.

Conclusion

Deep learning frameworks now provide a rigorous, scalable approach to predicting RBD evolution and escape mutations in viral pathogens of veterinary importance. Sequence-to-structure mapping, binding affinity prediction, and generative design collectively enable proactive surveillance and vaccine design. The integration of these computational tools with conventional serological and molecular assays will be essential to mitigate the impact of antigenic drift and spillover events in animal populations.

References

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