The effect of serial deletions of the Psi sequence on gene transduction efficiency and RNA packaging.

<p>A) Psi sequence of PMM.psi vector was deleted from 3′ end serially. The nucleotide position numbers were also shown in parentheses at the end of each mutant constructs. B) Lentiviruses produced from PMM1.psi deletion mutants were transduced to MT4 cells for 72 hr, and expression of EGFP was visualized by fluorescence microscopy and percentage of EGFP positive cells was quantified with FACS and indicated on each histogram. C) Transduction efficiency of each vector in MT4 cells was calculated from FACS data normalized with p24 ELISA. D) Viral RNA packaging efficiency was determined from qRT-PCR and p24 ELISA. All data are presented in comparison to EGFP control in One-way ANOVA, and data showing significant differences (p<0.001) are marked with three asterisks.