Cell culture and transfection

U1 (provided by Prof. Qinxue Hu, Wuhan Institute of Virology, Chinese Academy of Sciences) and OM10.1 cells (provided by Prof. Yongtang Zheng, Kunming Institute of Zoology, Chinese Academy of Sciences) were cultured in RPMI-1640 medium (Gibco) containing 10% heat inactivated FBS (Gibco). The HIV provirus DNA in U1 and OM10.1 was verified by PCR and sequencing. 293T cells (obtained from the Type Culture Collection of the Chinese Academy of Sciences, Shanghai) were maintained in DMEM (Gibco) with 10% FBS (Gibco). The cell lines have no mycoplasma contamination. Plasmids and Quantum Dots QDs were transfected using Nucleofector (Lonza) or TransIn EL Transfection Reagent (Transgene Biotech) in accordance with the manufacturer’s protocol. First, the plasmids pcDNA3-LplA (W37V) (1 µg, obtained from Addgene) and/or pcDNA3.1 (+)-BirA (3 µg) were transfected into 106 cells cultured in a confocal dish. After incubation overnight, the plasmids pcDNA3.1 (+)-TALE-N2-L (2 µg) and/or pcDNA3.1 (+)-TALE-N2-R (2 µg), and Tz1-QD625 (100 µM) and/or SA-QD525 (150 µM) were transfected into these cells. TCO2 (200 µM) and/or biotin (50 µM) were added into the culture medium after transfection. Following additional incubation for 6–12 h, the cells were cultured and imaged under a microscope equipped with a heated chamber at 37 °C with 5% CO2. TCO2 and Tz1 were synthesized following Liu et al.13