Singh M K, Pauza C D
Aaron Diamond AIDS Research Center, New York, New York 10016.
Virology. 1992 Jun;188(2):451-8. doi: 10.1016/0042-6822(92)90498-e.
Long-term human immunodeficiency virus type 1 (HIV-1) infection of the human monocytic cell line U937 resulted in a progressive loss of infectivity that was correlated with the accumulation of stable, extrachromosomal forms of viral DNA. Viral latency was also characterized by reduced levels of HIV-1 transcription. The structure and activity of extrachromosomal viral DNA (E-DNA) in a fully latent U937 cell line was investigated by molecular cloning and DNA transfection. The resulting 18-kb E-DNA clone was composed of an intact HIV-1 sequence flanked by 7 kb of host sequence to one side and 1 kb of host DNA to the other side. This configuration is the result of retroviral integration into a highly repetitive element of the Alu family. Transfection of the E-DNA clone resulted in the production of infectious virus, indicating that viral latency was not the result of mutations in the HIV-1 genome. Analysis of CCGG sites revealed extensive de novo methylation of viral sequences present within E-DNA. These results suggest that modification of extrachromosomal viral DNA sequences is a mechanism for HIV-1 latency in long-term infected U937 cells.
人类单核细胞系U937长期感染1型人类免疫缺陷病毒（HIV-1）导致感染性逐渐丧失，这与稳定的染色体外病毒DNA形式的积累相关。病毒潜伏还表现为HIV-1转录水平降低。通过分子克隆和DNA转染研究了完全潜伏的U937细胞系中染色体外病毒DNA（E-DNA）的结构和活性。得到的18 kb E-DNA克隆由一个完整的HIV-1序列组成，一侧侧翼有7 kb的宿主序列，另一侧有1 kb的宿主DNA。这种结构是逆转录病毒整合到Alu家族的一个高度重复元件的结果。E-DNA克隆的转染导致了感染性病毒的产生，表明病毒潜伏不是HIV-1基因组中突变的结果。对CCGG位点的分析揭示了E-DNA中存在的病毒序列广泛的从头甲基化。这些结果表明，染色体外病毒DNA序列的修饰是长期感染的U937细胞中HIV-1潜伏的一种机制。
