Sainz Bruno, LaMarca Heather L, Garry Robert F, Morris Cindy A
Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Tulane University Health Sciences Center, 1430 Tulane Avenue, SL-38, New Orleans, LA 70112, USA.
Virol J. 2005 Feb 23;2:14. doi: 10.1186/1743-422X-2-14.
Recent studies have shown that gamma interferon (IFN-gamma) synergizes with the innate IFNs (IFN-alpha and IFN-beta) to inhibit herpes simplex virus type 1 (HSV-1) replication in vitro. To determine whether this phenomenon is shared by other herpesviruses, we investigated the effects of IFNs on human cytomegalovirus (HCMV) replication.
We have found that as with HSV-1, IFN-gamma synergizes with the innate IFNs (IFN-alpha/beta) to potently inhibit HCMV replication in vitro. While pre-treatment of human foreskin fibroblasts (HFFs) with IFN-alpha, IFN-beta or IFN-gamma alone inhibited HCMV plaque formation by approximately 30 to 40-fold, treatment with IFN-alpha and IFN-gamma or IFN-beta and IFN-gamma inhibited HCMV plaque formation by 163- and 662-fold, respectively. The generation of isobole plots verified that the observed inhibition of HCMV plaque formation and replication in HFFs by IFN-alpha/beta and IFN-gamma was a synergistic interaction. Additionally, real-time PCR analyses of the HCMV immediate early (IE) genes (IE1 and IE2) revealed that IE mRNA expression was profoundly decreased in cells stimulated with IFN-alpha/beta and IFN-gamma (approximately 5-11-fold) as compared to vehicle-treated cells. Furthermore, decreased IE mRNA expression was accompanied by a decrease in IE protein expression, as demonstrated by western blotting and immunofluorescence.
These findings suggest that IFN-alpha/beta and IFN-gamma synergistically inhibit HCMV replication through a mechanism that may involve the regulation of IE gene expression. We hypothesize that IFN-gamma produced by activated cells of the adaptive immune response may potentially synergize with endogenous type I IFNs to inhibit HCMV dissemination in vivo.
最近的研究表明，γ干扰素（IFN-γ）与天然干扰素（IFN-α和IFN-β）协同作用，在体外抑制单纯疱疹病毒1型（HSV-1）复制。为了确定这种现象是否也存在于其他疱疹病毒中，我们研究了干扰素对人巨细胞病毒（HCMV）复制的影响。
我们发现，与HSV-1一样，IFN-γ与天然干扰素（IFN-α/β）协同作用，在体外有效抑制HCMV复制。单独用IFN-α、IFN-β或IFN-γ预处理人包皮成纤维细胞（HFFs）可使HCMV斑块形成抑制约30至40倍，而用IFN-α和IFN-γ或IFN-β和IFN-γ处理分别使HCMV斑块形成抑制163倍和662倍。等效线图分析证实，IFN-α/β和IFN-γ对HFFs中HCMV斑块形成和复制的抑制作用是一种协同相互作用。此外，对HCMV立即早期（IE）基因（IE1和IE2）的实时PCR分析显示，与载体处理的细胞相比，用IFN-α/β和IFN-γ刺激的细胞中IE mRNA表达显著降低（约5至11倍）。此外，如蛋白质印迹和免疫荧光所示，IE mRNA表达的降低伴随着IE蛋白表达的降低。
这些发现表明，IFN-α/β和IFN-γ通过一种可能涉及IE基因表达调控的机制协同抑制HCMV复制。我们推测，适应性免疫反应激活细胞产生的IFN-γ可能与内源性I型干扰素协同作用，在体内抑制HCMV传播。
