To transduce CEMss and CEMss-CCR5 cells, 1 × 10 5 CEMss or CEMss-CCR5 cells and 2 × 10 6 TU of one of the lentiviral vectors containing pRRL-scFv (X5 or AB65)/hinge/his-tag/DAF or pRRL-scFv(X5 or AB65)/ hinge/his-tag were added onto 24-well tissue culture plate in the presence of 8 μg/ml of polybrene (Sigma).