Screening and Mechanism of Trapping Ligand Antagonist Peptide for Chemokine Receptor US28 of Human Cytomegalovirus

Purpose: The aim of the present study was to develop peptide H9 as an efficient antagonist of human cytomegalovirus (HCMV) chemokine receptor US28.
Methods: US28 gene was amplified from HCMV, and a stable expression system was constructed using NIH/3T3 cells. Interaction between peptide H9 and receptor US28 was tested by enzyme-linked immunosorbent assay. Flow cytometry was used to determine intracellular concentrations of Ca²⁺, and the possible role of H9 as an antagonist was evaluated by anti-viral experiments.
Results: H9 interacts with the US28 receptor and prevents an increase of Ca²⁺ resulting from an interaction of chemokine with its receptor. Anti-viral assays showed that H9 could inhibit cytopathic effects of HCMV. AD169 infection (EC₅₀ = 0.46 ng/ml), and the production of pp65 antigen were strongly inhibited with an EC₅₀ value of 0.34 ng/ml.
Conclusion: The results demonstrate that H9 is an antagonist of US28, suggesting a possible role as a treatment for HCMV.

Keywords
Human cytomegalovirus, US28, Peptide H9, Trapping receptor/ligand, Antagonist