Determining the molecular drivers of species-specific interferon-stimulated gene product 15 interactions with nairovirus ovarian tumor domain proteases
(A) Comparison of KUPEV OTU-sheep ISG15, ERVEV OTU-C-mouse ISG15 (PDB ID 5JZE), GANV OTU-sheep ISG15, and CCHFV OTU-human ISG15 (PDB ID 3PHX) interactions between residue 130/128 of ISG15 and residues 77–80 of the OTU highlighting the variable sensitivity of this region. Cleavage assays show the relative impact of mutations in human proISG15 and northern tree shrew proISG15 on reactions with the CCHFV, ERVEV, KUPEV, and GANV OTUs. (B) KUPEV OTU-C-sheep ISG15 and CCHFV OTU-C-human ISG15 interactions at points that differ between sheep ISG15 and human ISG15. Cleavage assays show the impact of performing residue swaps in human proISG15 and Egyptian fruit bat proISG15 on reactions with CCHFV, ERVEV, KUPEV, and GANV. Samples from each timepoint were run on BioRad Mini-PROTEAN® TGX Stain-Free™ gels and visualized as described in the Materials and Methods.