Schematic representation of fluorescently labeled semi-replicative retroviral vectors. The env open reading frame was replaced with the gene for red fluorescent protein (RFP) in the gag/pol-expressing construct, GAG/POL-RFP, and GFP-tagged Env was expressed from a packagable vector (GFP-Env). Positions of primers used to analyze the appearance of replication-competent viruses and the stability of the inserted GFP sequences by polymerase chain reactions (PCR) are indicated as p1 to p4. SA: splice acceptor site; SD: splice donor site.
Sliva et al. Virology Journal 2004 1:14 doi:10.1186/1743-422X-1-14