title: Inhibition of infection and replication of human herpesvirus 8 in microvascular endothelial cells by alpha interferon and phosphonoformic acid.
abstract: Infection of endothelial cells with human herpesvirus 8 (HHV-8) is an essential event in the development of Kaposi's sarcoma. When primary microvascular endothelial cells (MECs) were infected with HHV-8 at a low multiplicity of infection, considerable latent replication of HHV-8 occurred, leading to a time-dependent increase in the percentage of virus-infected cells that was accompanied by cellular spindling and growth to a high density with loss of contact inhibition. Only a low percentage of MECs supported lytic replication of HHV-8 and produced infectious virus. Phosphonoformic acid blocked production of infectious virus but did not inhibit the rapid expansion of latently infected MECs. Pretreatment of MECs with alpha interferon (IFN-alpha) prior to infection effectively reduced HHV-8 viral gene expression, latent replication, and production of infectious virus. High levels of the double-stranded RNA activated protein kinase (PKR) were expressed in HHV-8-infected cells, and incubation with IFN-alpha increased PKR expression more in virus-infected cells than in uninfected cells. MECs that were immortalized with simian virus 40 large-T antigen differed from nonimmortalized MECs in their response to infection with HHV-8 and demonstrated that cells with elevated levels of expression of antiviral transcripts expressed viral transcripts at reduced levels. These studies demonstrate that MECs respond to HHV-8 with enhanced expression of cellular antiviral genes and that augmentation of innate antiviral defenses with IFN-alpha is a more effective strategy than inhibition of viral lytic replication to protect MECs from infection with HHV-8 and to restrict proliferation of virus-infected MECs.
authors.affiliation: Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA.
authors.forename: Laurie T
authors.initials: LT
authors.lastname: Krug
authors.forename: Veronika P
authors.initials: VP
authors.lastname: Pozharskaya
authors.forename: Yimin
authors.initials: Y
authors.lastname: Yu
authors.forename: Naoki
authors.initials: N
authors.lastname: Inoue
authors.forename: Margaret K
authors.initials: MK
authors.lastname: Offermann
mesh_terms: D000956:Antigens, Viral; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000821:virology*; D017245:Foscarnet / Q000494:pharmacology*; D019288:Herpesvirus 8, Human / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000032:analysis; D019384:Nucleic Acid Synthesis Inhibitors; D014779:Virus Replication / Q000187:drug effects*; D019892:eIF-2 Kinase / Q000096:biosynthesis
chemical_list: D000956:Antigens, Viral; D016898:Interferon-alpha; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; C109540:latency-associated nuclear antigen; D017245:Foscarnet; D019892:eIF-2 Kinase