Novel cell type-specific antiviral mechanism of interferon gamma action in macrophages.
Interferon (IFN)-gamma and macrophages (Mphi) play key roles in acute, persistent, and latent murine cytomegalovirus (MCMV) infection. IFN-gamma mechanisms were compared in embryonic fibroblasts (MEFs) and bone marrow Mphi (BMMphi). IFN-gamma inhibited MCMV replication in a signal transducer and activator of transcription (STAT)-1alpha-dependent manner much more effectively in BMMphi (approximately 100-fold) than MEF (5-10-fold). Although initial STAT-1alpha activation by IFN-gamma was equivalent in MEF and BMMphi, microarray analysis demonstrated that IFN-gamma regulates different sets of genes in BMMphi compared with MEFs. IFN-gamma inhibition of MCMV growth was independent of known mechanisms involving IFN-alpha/beta, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase RNA activated (PKR), RNaseL, and Mx1, and did not involve IFN-gamma-induced soluble mediators. To characterize this novel mechanism, we identified the viral targets of IFN-gamma action, which differed in MEF and BMMphi. In BMMphi, IFN-gamma reduced immediate early 1 (IE1) mRNA during the first 3 h of infection, and significantly reduced IE1 protein expression for 96 h. Effects of IFN-gamma on IE1 protein expression were independent of RNaseL and PKR. In contrast, IFN-gamma had no significant effects on IE1 protein or mRNA expression in MEFs, but did decrease late gene mRNA expression. These studies in primary cells define a novel mechanism of IFN-gamma action restricted to Mphi, a cell type key for MCMV pathogenesis and latency.
Presti
R M
RM
Department of Pathology and Immunology and the Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Popkin
D L
DL
Connick
M
M
Paetzold
S
S
Virgin
H W
HW
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D001854:Bone Marrow Cells / Q000821:virology*; D003587:Cytomegalovirus / Q000187:drug effects*; D004722:Endoribonucleases / Q000378:metabolism; D005347:Fibroblasts / Q000821:virology; D020869:Gene Expression Profiling; D050832:Interferon-Stimulated Gene Factor 3; D016898:Interferon-alpha / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D008264:Macrophages / Q000821:virology*; D051379:Mice; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger; D014157:Transcription Factors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism
D000998:Antiviral Agents; D050832:Interferon-Stimulated Gene Factor 3; D016898:Interferon-alpha; D012333:RNA, Messenger; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C079868:gamma interferon activation factor; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D019892:eIF-2 Kinase; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease