CMV-Cre-GFP-Puro Lentivirus

Lentiviral vectors (LV) have a higher potential gene capacity (≤15 kbp) and a broad tissue tropism, which can be achieved by using a variety of viral envelopes. An important finding of LV is that these viruses are able to infect both dividing and non-dividing cells and integrate into host chromosomes. Therefore, LV vectors are able to stably and long-term express transcripts. However, this can also be a disadvantage, as they may activate oncogenes close to LV integration, or cause silencing of cellular essential genes. LVs include viruses from several different genera: simian immunodeficiency virus, human immunodeficiency virus (HIV-1 and HIV-2), and various non-primate LVs. The first developed and most commonly used lentiviral vector is based on HIV-1, which can efficiently transduce non-dividing cells. Over the years, three generations of HIV-1-based LVs have been produced due to biosafety issues with the use of highly infectious viruses. However, the backbone of HIV-1 can be further modified. Vectors can be created by combining two viruses, fusing the backbone of one virus and the expression elements of another virus, or deleting partial sequences of HIV-1. In addition, regulation of the transgene expression cassette is critical for clinical application. The transgene level can be adjusted to increase or decrease according to clinical needs to reduce adverse effects such as overexpression of the therapeutic gene. However, this is a multivariable issue involving vector copy number, integration site, and promoter selection. The lentiviral vector expression cassette with the transgene of interest can be adjusted as needed. The basic components of the lentiviral vector include enhancers/upstream promoters, promoters, target genes, inverted terminal repeats/long terminal repeats (LTRs), and polyA signal sequences. Other commonly used cis-acting elements include introns and post-transcriptional regulatory elements (PREs) to ensure high levels of transgene expression.