Molecular Characterization and Genomic Diversity of SARS-CoV-2 Spike Gene Variants Circulating in Iraq: Mutational...

The spike (S) gene of SARS-CoV-2 is pivotal to the processes of cell entry, immune evasion, and the adaptation of the host.

This study aimed to comprehensively characterize the SARS-CoV-2 spike gene variants circulating in Iraq and assess the functional consequences of their mutations on ACE2 receptor affinity, RBD-mediated immune escape, and viral transmissibility. It represents the first integrative genomic and functional profiling of Iraqi SARS-CoV-2 spike variants, providing novel regional insights into viral adaptation and evolution.

Whole-genome sequencing was performed on Iraqi SARS-CoV-2 isolates, followed by mutation profiling, phylogenetic classification, and comparison with global datasets. Key spike mutations-N501Y, P681R, D614G, and E484K-were analyzed to assess their structural and functional implications.

Iraqi isolates clustered mainly within the Delta (21J) and 20A lineages. The mutations N501Y (91.7%), P681R (75%), and D614G (100%) were prevalent, enhancing viral binding and transmission, while E484K was absent, suggesting limited immune escape compared to Omicron-like variants.

The absence of E484K and the predominance of transmission-enhancing mutations indicate that Iraqi SARS-CoV-2 isolates favor adaptation through increased ACE2 affinity rather than extensive immune evasion. These findings underscore the importance of regional genomic surveillance to inform vaccination strategies and public health responses.