Tong-Starksen S E, Sepp T, Pagtakhan A S
Department of Medicine, University of California-San Francisco.
J Virol. 1996 Jan;70(1):595-9. doi: 10.1128/JVI.70.1.595-599.1996.
Caprine arthritis-encephalitis virus (CAEV) is a lymphotropic lentivirus whose replication increases during monocyte maturation. We examined gene expression directed by the CAEV long terminal repeat (LTR) in a promonocytic cell line stimulated with several agents. Our results demonstrate that the CAEV LTR is activated by treatment of immature monocytes with gamma interferon (IFN-gamma) or a phorbol ester but not with tumor necrosis factor alpha or lipopolysaccharide. The cis-acting element in the LTR for the IFN-gamma response localizes to a duplicated 70-bp motif that contains an IFN-gamma response element, the gamma-activated site. One copy of the motif is necessary and sufficient for the response to IFN-gamma. Multiple copies contribute to basal transcriptional activity in the context of a heterologous promoter. This IFN-gamma response element in the CAEV LTR differs from the element required for the response to phorbol esters. Thus, activation of the CAEV LTR in monocytes that are stimulated by IFN-gamma, a cytokine that is secreted in response to viral infections, could contribute to conversion from latent to high-level viral replication in infected hosts.
山羊关节炎-脑炎病毒（CAEV）是一种嗜淋巴细胞慢病毒，其复制在单核细胞成熟过程中增加。我们检测了在几种试剂刺激的原单核细胞系中由CAEV长末端重复序列（LTR）指导的基因表达。我们的结果表明，CAEV LTR可被用γ干扰素（IFN-γ）或佛波酯处理未成熟单核细胞激活，但不能被肿瘤坏死因子α或脂多糖激活。LTR中对IFN-γ应答的顺式作用元件定位于一个重复的70碱基基序，该基序包含一个IFN-γ应答元件，即γ激活位点。该基序的一个拷贝对于对IFN-γ的应答是必需且足够的。在异源启动子的背景下，多个拷贝有助于基础转录活性。CAEV LTR中的这个IFN-γ应答元件不同于对佛波酯应答所需的元件。因此，在被IFN-γ刺激的单核细胞中CAEV LTR的激活，IFN-γ是一种响应病毒感染而分泌的细胞因子，可能有助于在感染宿主中从潜伏性病毒复制转变为高水平病毒复制。
