Small glycomimetic antagonists of the cytomegalovirus glycoprotein UL141 prevent binding to TRAIL death receptor.

Abstract

Human cytomegalovirus (HCMV) UL141 inhibits immune recognition of virally infected cells by natural killer (NK) cells and cytotoxic T cells through modulation of cellular receptors (e.g., TRAIL-R2/-R1, CD155, CD112). Recent findings suggest that UL141 is also a critical component of the HCMV virion, that further emphasizing its significance. In this study, we aimed to develop a small synthetic compound as a UL141 antagonist. Building on our crystal structure analysis, we designed compounds to specifically bind viral UL141, thereby blocking its interaction with target receptors thus inhibiting its immunoevasive functions. We evaluated a small library of synthesized compounds composed of diverse saccharide units conjugated with non-saccharide moieties, such as non-ionic glycolipids, pyrrolidines, and 'click' conjugates. An ELISA-like TMB binding assay, coupled with dynabeads coating, was employed to assess the ability of these compounds to inhibit TRAIL-R2 binding in vitro. The most promising compounds capable of inhibiting complex formation were further analyzed using surface plasmon resonance (SPR). Compound 18 exhibited the strongest binding affinity to UL141, with KD of 2.93 μM. Molecular docking studies identified specific binding sites on UL141, and the fragmented molecular orbital (FMO) method was applied to evaluate interaction energy patterns between the antagonist and the UL141 protein. Mutational analysis was conducted to validate the identified binding sites on UL141. Additionally, cellular cytotoxicity assays were performed to confirm the non-toxic properties of these compounds. Collectively, our findings suggest that synthetic glycomimetics represent promising candidates for targeting the viral glycoprotein HCMV UL141, thereby disrupting TRAIL death receptor signaling thus mitigating viral activity.