Human cytomegalovirus US28 facilitates cell-to-cell viral dissemination

Viruses. 2014 Mar 12;6(3):1202-18. doi: 10.3390/v6031202.


Human cytomegalovirus (HCMV) encodes a number of viral proteins with homology to cellular G protein-coupled receptors (GPCRs). These viral GPCRs, including US27, US28, UL33, and UL78, have been ascribed numerous functions during infection, including activating diverse cellular pathways, binding to immunomodulatory chemokines, and impacting virus dissemination. To investigate the role of US28 during virus infection, two variants of the clinical isolate TB40/E were generated: TB40/E-US28(YFP) expressing a C-terminal yellow fluorescent protein tag, and TB40/E-FLAG(YFP) in which a FLAG-YFP cassette replaces the US28 coding region. The TB40/E-US28(YFP) protein localized as large perinuclear fluorescent structures at late times post-infection in fibroblasts, endothelial, and epithelial cells. Interestingly, US28(YFP) is a non-glycosylated membrane protein throughout the course of infection. US28 appears to impact cell-to-cell spread of virus, as the DUS28 virus (TB40/E-FLAG(YFP)) generated a log-greater yield of extracellular progeny whose spread could be significantly neutralized in fibroblasts. Most strikingly, in epithelial cells, where dissemination of virus occurs exclusively by the cell-to-cell route, TB40/E-FLAG(YFP) (DUS28) displayed a significant growth defect. The data demonstrates that HCMV US28 may contribute at a late stage of the viral life cycle to cell-to-cell dissemination of virus.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artificial Gene Fusion
  • Bacterial Proteins / analysis
  • Bacterial Proteins / genetics
  • Cells, Cultured
  • Cytomegalovirus / genetics
  • Cytomegalovirus / growth & development
  • Cytomegalovirus / isolation & purification
  • Cytomegalovirus / physiology*
  • Cytoplasm / chemistry
  • Endothelial Cells / virology
  • Epithelial Cells / virology
  • Fibroblasts / virology
  • Gene Deletion
  • Genes, Reporter
  • Humans
  • Luminescent Proteins / analysis
  • Luminescent Proteins / genetics
  • Receptors, Chemokine / genetics
  • Receptors, Chemokine / metabolism*
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / genetics
  • Staining and Labeling
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*


  • Bacterial Proteins
  • Luminescent Proteins
  • Receptors, Chemokine
  • Recombinant Fusion Proteins
  • US28 receptor, Cytomegalovirus
  • Viral Proteins
  • yellow fluorescent protein, Bacteria