HCMV NEC inhibitor GK1 is a small molecule inhibitor of HCMV nuclear egress complex (NEC) subunit interactions, interferes with the interaction of UL50 and UL53 with IC50 of 5.3 uM in HTRF assays, exerts selective antiviral activity.
GK1 does not show inhibition in an HTRF assay for interactions of mouse cytomegalovirus NEC subunits, and not show meaningful inhibition in the HSV-1 P30-UL42.
GK1 inhibits HCMV plaque formation with ED50 of 0.83 uM in human foreskin fibroblasts (HFFs), exhibits less potent anti-HSV-1 activity (ED50=11 uM).
GK1 inhibits late events in the viral replication cycle and modestly affect co-localization of UL50 and UL53.
The covalent interaction of GK1 with UL53 cysteine 214 (C214) is crucial for inhibition of NEC interactions in vitro, and UL53 cysteine 214 confers resistance to GK1.
The HCMV NEC is a virally encoded, two-subunit protein heterodimer, comprised of an INM-anchored subunit (UL50) and a nucleoplasmic subunit (UL53), which, based on work from other herpesviruses, forms higher order hexagonal arrays to promote budding.
HCMV NEC is crucial for viral replication and differs markedly from host proteins, important properties for an antiviral drug target.