title: Effective inhibition of human cytomegalovirus gene expression and growth by intracellular expression of external guide sequence RNA.
abstract: RNase P complexed with external guide sequence (EGS) represents a novel nucleic-acid-based gene interference approach to modulate gene expression. In this study, a functional EGS RNA was constructed to target the overlapping mRNA region of two human cytomegalovirus (HCMV) capsid proteins, the capsid scaffolding protein (CSP) and assemblin. The EGS RNA was shown to be able to direct human RNase P to cleave the target mRNA sequence efficiently in vitro. A reduction of approximately 75%-80% in the mRNA and protein expression levels of both CSP and assemblin and a reduction of 800-fold in viral growth were observed in human cells that expressed the functional EGS, but not in cells that either did not express the EGS or produced a "disabled" EGS that carried nucleotide mutations that precluded RNase P recognition. The action of the EGS is specific as the RNase P-mediated cleavage only reduces the expression of the CSP and assemblin but not other viral genes examined. Further studies of the antiviral effects of the EGS indicate that the expression of the functional EGS has no effect on HCMV genome replication but blocks viral capsid maturation, consistent with the notion that CSP and assemblin play essential roles in HCMV capsid formation. Our study provides the first direct evidence that EGS RNAs effectively inhibit HCMV gene expression and growth. Moreover, these results demonstrate the utility of EGS RNAs in gene therapy applications, including the treatment of HCMV infection by inhibiting the expression of virus-encoded essential proteins.
authors.affiliation: Division of Infectious Diseases, School of Public Health, 140 Warren Hall, University of California, Berkeley, CA 94720, USA.
authors.forename: Hongjian
authors.initials: H
authors.lastname: Li
authors.forename: Phong
authors.initials: P
authors.lastname: Trang
authors.forename: Kihoon
authors.initials: K
authors.lastname: Kim
authors.forename: Tianhong
authors.initials: T
authors.lastname: Zhou
authors.forename: Sean
authors.initials: S
authors.lastname: Umamoto
authors.forename: Fenyong
authors.initials: F
authors.lastname: Liu
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008954:Models, Biological; D012367:RNA, Viral / Q000378:metabolism; D043262:Ribonuclease P / Q000737:chemistry; D012697:Serine Endopeptidases / Q000378:metabolism*; D014162:Transfection; D014779:Virus Replication / Q000235:genetics; D058727:RNA, Small Untranslated
chemical_list: D036022:Capsid Proteins; D012367:RNA, Viral; D043262:Ribonuclease P; D012697:Serine Endopeptidases; C071910:assemblin; D058727:RNA, Small Untranslated