摘要
When using recombinant retroviruses for gene transduction, it is necessary to have a measurement of the concentration of virus particles in the medium conditioned by virus-producing cells (i.e., the viral titer). In the case of viruses encoding selectable markers, this can readily be determined by infecting a susceptible cell line (usually 3T3 fibroblasts), culturing in selection medium, and scoring colonies of resistant cells ( Chapter 3, this volume), which gives a concentration of virus particles in the preparation as a number of colony-forming units/mL (CFU/mL). In cases in which the gene of interest is not selectable, quantitation can still be achieved by the use of recombinant viruses additionally encoding a selectable marker under the control of a separate promoter ( Chapter 1). In some cases a selectable gene may be desirable, but there is evidence indicating that in viruses possessing two transcriptional units expression from each is depressed (1,2). Thus, for maximum viral titer and maximum gene expression in the target cell, the virus construct of choice will encode a single gene. Other means of estimating viral titers are then required.
摘要译文
当使用重组逆转录病毒进行基因转导时，必须测量由产生病毒的细胞调节的培养基中的病毒颗粒浓度（即病毒滴度）。在编码选择标记的病毒的情况下，这可以通过感染易感细胞系（通常是3T3成纤维细胞），在选择培养基中培养和对抗性细胞的集落进行评分（第3章，本卷）来确定，其浓度为制备中的病毒颗粒为多个菌落形成单位/ mL（CFU / mL）。在感兴趣的基因不可选择的情况下，仍然可以通过使用在单独的启动子控制下另外编码选择标记的重组病毒来实现定量（第1章）。在某些情况下，可选择的基因可能是合乎需要的，但有证据表明，在具有两个转录单位的病毒中，每个转录单位的表达都被抑制（1,2）。因此，为了在靶细胞中获得最大的病毒滴度和最大基因表达，所选择的病毒构建体将编码单个基因。然后需要其他估计病毒滴度的方法。
Colin D. Porter[1]. Methods of Titrating Nonselectable Recombinant Retroviruses. Practical Molecular Virology[M].DE: Springer, 1992: 45-48