Hi. I'm trying to produce lentivirus.
However, I had found that there are several kinds of lentiviral transfer vectors containing LTR pair on both hands of GOI coding region.
1) 5'LTR and 5'LTR
2) 5'LTR and 3'LTR
3) 3'LTR and 3'LTR(delta U3)
Are there anyone knowing the difference among them?
The second-generation vectors, however, still carry the transcriptionally active LTR
elements that could induce the homologous recombination between the vector genome and wild-type HIV-1. This would be particularly problematic if the lentiviral vectors are used for gene therapy of HIV/AIDS. Thus, further improvements were made in the third-generation lentiviral vectors. To minimize the transcriptional activity of the LTR in transduced cells, the enhancer/promoter unit was deleted from the U3 region of the 3’ LTR in transfer vector plasmids. During reverse transcription in the transduced cells, this deletion is transferred to
the 5’ LTR of the lentiviral DNA, thereby reducing promoter activity of the integrated provirus (self-inactivating [SIN] vector) (Miyoshi et al., 1998; Zufferey et al., 1998). Additionally, the U3’region of the 5’ LTR in the transfer vector plasmid was replaced with the cytomegalovirus (CMV) promoter, which enabled Tat-independent transcription of the lentiviral vector genome in producer cells (Dull et al., 1998; Miyoshi et al., 1998). In these SIN vectors, there is no compete HIV-1 U3 sequence. Moreover, expression of Rev protein is directed by a separate plasmid, but not by the packaging plasmid encoding gag and pol genes (Wagner et al., 2000).(From VIRAL GENE THERAPY edited by Ke XU.)
