Lentiviral vector construct and use of UF units with different MWCOs for concentration of LVs. (A) Schematic representation of lentiviral vector used. eGFP, enhanced green fluorescent protein; CMV, promoter from cytomegalovirus; WPRE, posttranscriptional regulatory element of woodchuck hepatitis virus; cPPT, central polypurine tract; LTR, long terminal repeat; black triangle, mutation in 3' LTR, leading to self inactivation (SIN vector). (B) Comparison of Vivaspin20 UF units with different MWCOs: 1,000 ml of cell culture SN were purified using the large MAs. The elution fraction was desalted with Vivaspin20 UF units with MWCO of 100,000 (100 K) or 300,000 (300 K). The biological titer was determined by FACS-analysis and the recovery rate (%) was calculated. n = 4, mean + SEM. * 0.05 ≥ p > 0.01.