Retroviral Delivery of ECM Genes to Cells - Methods in Molecular Biology: Extracellular Matrix Protocols - page 189

Fig. 1. Packaging of infectious, but replication incompetent, virus. The retroviral
vector is transfected into packaging cells that provides viral proteins, gag, pol, and
env, necessary for particle formation, which have been deleted in the recombinant
viral vector. The full-length viral transcript containing the gene of interest is packaged
into viral particle upon binding of capsid protein to the sequence. The virus released

from packaging cells is infectious but lacks the viral genes, thus preventing retroviral
production from subsequently infected cells.

ψ

NL-Homepage. html) at Stanford University. Previously, a production of high-
titer recombinant virus required laborious and lengthy processes: transfection
of retroviral vector into the packaging cells, selection of transfected cells by
antibiotic resistance, and cloning of a high-titer producer cells. The

NX pack-
aging cells are based on the 293T cell line, a human embryonic kidney line
transformed with adenovirus E1a and carrying a temperature sensitive simian
virus large T antigen (5) . The unique feature of this cell line is that a high
frequency of transfection (greater than 50%) can be achieved by either calcium
phosphate or lipid-based transfection. Owing to an efficient transfection, high-
titer recombinant virus can be generated by transient transfection of retroviral
vector into the

Φ

Φ NX packaging cells. The advantages over previous, stably