Purifying Selection Constrains MERS-CoV ORF4a: Low-Frequency Variants at MDA5-Binding Y14, Dimeric L15, and Structural P18 Mildly Attenuate IFN Antagonism

This dataset comprises a high-quality multiple sequence alignment of 481 MERS-CoV ORF4a protein sequences, curated from global public repositories, and used to assess within-host variation at three functionally critical residues: Y14 (MDA5-binding site), L15 (dimer interface), and P18 (structural proline). The accompanying analysis files include: Full alignment (MERSCoV_ORF4a_aligned.fasta)Extracted variant subsets for Y14, L15, and P18 non-reference allelesFunctional impact report predicting effects on IFN antagonismMinor variant frequency and conservation metrics All variants detected are low-frequency (<1.3%) and predicted to reduce, not enhance, immune evasion function, indicating strong purifying selection and absence of adaptive evolution in probably congregation settings. No gain-of-function mutations were observed. This resource supports genomic surveillance of MERS-CoV accessory protein stability and serves as a baseline for detecting future shifts in innate immune antagonism potential. Study by: Tahir HB