Richardson J H, Child L A, Lever A M
Department of Medicine, University of Cambridge, Addenbrooke's Hospital, United Kingdom.
J Virol. 1993 Jul;67(7):3997-4005. doi: 10.1128/JVI.67.7.3997-4005.1993.
cis elements required for the encapsidation of human immunodeficiency virus type 1 (HIV-1) RNA have been investigated by using a replication-competent helper virus to package a series of HIV-1-based vectors which had been stably transfected into human CD4 T-cell lines. A previously identified packaging signal in the 5' leader region was not sufficient for the encapsidation of small vectors containing heterologous genes. In contrast, vectors containing additional gag and env sequences were packaged with high efficiency and transduced into CD4-expressing target cells with titers exceeding 10(4) CFU/ml. The presence of gag sequences did not enhance vector packaging efficiency. A 1.1-kb env gene fragment encompassing the Rev-responsive element was absolutely required for the expression and encapsidation of vectors containing cis-acting repressive sequences and appeared also to contain an important packaging signal. Vectors as small as 2.6 kb were successfully packaged in this system. The presence of abundant, packageable vector RNA did not appear to interfere with encapsidation of the wild-type HIV-1 genome, suggesting that HIV-1 RNA packaging capacity is not saturated during acute infection.
通过使用具有复制能力的辅助病毒来包装一系列已稳定转染到人CD4 T细胞系中的基于HIV-1的载体，对人类免疫缺陷病毒1型（HIV-1）RNA衣壳化所需的顺式元件进行了研究。5'前导区中先前鉴定的包装信号不足以使含有异源基因的小载体进行衣壳化。相比之下，含有额外gag和env序列的载体被高效包装，并以超过10(4) CFU/ml的滴度转导到表达CD4的靶细胞中。gag序列的存在并未提高载体包装效率。包含Rev反应元件的1.1 kb env基因片段对于含有顺式作用抑制序列的载体的表达和衣壳化是绝对必需的，并且似乎还包含一个重要的包装信号。小至2.6 kb的载体在该系统中成功包装。大量可包装的载体RNA的存在似乎并未干扰野生型HIV-1基因组的衣壳化，这表明在急性感染期间HIV-1 RNA的包装能力并未饱和。
