应用离心方法提高杆状病毒对哺乳动物细胞转导实验效率

Improving Baculovirus Transduction of Mammalian Cells by Spinoculation

摘要:

重组杆状病毒作为一种对哺乳动物细胞的新型基因转移载体已获得了日益广泛的应用。为进一步提高转导实验的效率，本研究利用已构建的带有CMV启动子-增强型绿色荧光蛋白（eGFP）表达盒的重组杆状病毒BacV-CMV-EGFPA，在CV-1细胞中探索了应用离心方法提高转导实验效率的可行性。结果显示离心方法可显著提高单位时间内重组杆状病毒对哺乳动物细胞的转导效率，同时不会对靶细胞造成损伤。通过对离心时间、离心后孵育时间、病毒上清的稀释缓冲液的进一步摸索优化，结果显示病毒上清以PBS为稀释缓冲环境室温600g水平离心1h即可获得高水平的转导效率，优于在PBS环境中27℃孵育8h的效果。该方法可在获得高转导效率的同时显著缩短实验时间，具有快捷、高效、低损伤的特点，可作为一种常规操作方法用于日常实验。本研究进一步应用该方法对多种不同来源和类型的哺乳动物细胞株进行基因转导，结果显示该方法可适用于多数不同种属和组织来源的哺乳动物细胞，其中对贴壁细胞的效果最为显著。

Abstract:

Recently many reports have described that recombinant baculovirus could serve as a new gene transfer vehicle for mammalian cells with many unique advantages. In this study, the constructed recombinant baculovirus BacV-CMV-EGFPA containing the enhanced green fluorescent protein (eGFP) gene driven by CMV promoter was used to explore the feasibility of improving the efficiencies of transduction experiment in CV-1 cells by centrifugal method. Refer to the centrifugal transduction protocol of recombinant lentivirus, CV-1 cells were incubated with the culture supernatant of Sf-21 cells infected by BacV-CMV-EGFPA (moi=30) and then centrifuged at 600g for 1h at RT, reporter gene transfer and expression efficiencies were analyzed by flow cytometry (FCM) 48h post transduction. Results showed that centrifugal method can achieve higher gene delivery and expression efficiencies than transduction by simple virus-cell mixing for 4h at 27℃ with least impairment to cell viability. The centrifugal transduction protocol was further optimized by testing different centrifugal times, post-centrifugation incubation times and surrounding solutions. We found that centrifugation at 600g for 1h at RT is sufficient to achieve the highest transduction efficiencies in target cells and PBS is more suitable than other surrounding solutions. Compared with previous protocol in which tranduction occurs for 4～8h at 27℃, centrifugal method developed in this study could achieve more higher transduction efficiencies in more shorter time. Nine different mammalian cell lines (CV-1, 293FT, HepG2, 293T, CHO, C127, MT4, H9, Molt-4) were used to investigate the feasibility of delivering exogenous genes into different mammalian cells with the BacV-CMV-EGFPA supernatant (moi=30) at 600g for 1h in PBS surrounding solution at RT. Results showed that most mammalian cell lines used in this study could be effectively transduced with recombinant baculoviruses by centrifugal method, and more higher and satisfactory transduction efficiencies could be achieved in primate adherent culture cells than in suspended culture cells. These results show that the baculovirus centrifugal transduction protocol have notable advantages: more rapid, efficient and nontoxic, and could be easily used in daily common experiments.