Yu S S, Kim J M, Kim S
Institute for Molecular Biology and Genetics, Seoul National University, Seoul, Korea.
Gene Ther. 2000 May;7(9):797-804. doi: 10.1038/sj.gt.3301164.
Almost all currently available retroviral vectors based on murine leukemia virus (MLV) contain one or more viral coding sequences. Because these sequences are also present in the packaging genome, it has been suggested that homologous recombination may occur between the same nucleotide sequence in the packaging genome and the vector, resulting in the production of replication competent retrovirus (RCR). Up until now, it has been difficult to completely remove viral coding sequences since some were thought to be involved in the optimum function of the retroviral vector. For example, the gag coding sequence present in almost all available retroviral vectors has been believed to be necessary for efficient viral packaging, while the pol coding sequence present in the highly efficient vector MFG has been thought to be involved in achieving the high levels of gene expression. However, we have now developed a series of retroviral vectors that are absent of any retroviral coding sequences but produce even higher levels of gene expression without compromising viral titer. In these vectors, the intron and exon sequences from heterologous cellular or viral genes are present. When compared with the well-known MLV-based vectors, some of these newly developed vectors have been shown to produce significantly higher levels of gene expression for a longer period. In an experimental system that can maximize the production of RCR, our newly constructed vectors produced an absence of RCR. These vectors should prove to be safer than other currently available retroviral vectors containing one or more viral coding sequences.
几乎所有目前可用的基于鼠白血病病毒（MLV）的逆转录病毒载体都包含一个或多个病毒编码序列。由于这些序列也存在于包装基因组中，有人提出在包装基因组和载体中的相同核苷酸序列之间可能发生同源重组，从而产生具有复制能力的逆转录病毒（RCR）。到目前为止，完全去除病毒编码序列一直很困难，因为一些序列被认为与逆转录病毒载体的最佳功能有关。例如，几乎所有可用逆转录病毒载体中存在的gag编码序列被认为是高效病毒包装所必需的，而高效载体MFG中存在的pol编码序列被认为与实现高水平的基因表达有关。然而，我们现在已经开发出一系列逆转录病毒载体，它们没有任何逆转录病毒编码序列，但在不影响病毒滴度的情况下能产生更高水平的基因表达。在这些载体中，存在来自异源细胞或病毒基因的内含子和外显子序列。与众所周知的基于MLV的载体相比，这些新开发的载体中的一些已被证明能在更长时间内产生显著更高水平的基因表达。在一个能使RCR产生最大化的实验系统中，我们新构建的载体未产生RCR。这些载体应该比其他目前可用的含有一个或多个病毒编码序列的逆转录病毒载体更安全。
