Retroviruses have a positive-strand nonsegmented RNA genome that undergoes reverse transcription to a double-stranded DNA form prior to random integration into the genome of a target cell in a form called the provirus. The provirus is transcribed into mRNAs that encode the viral proteins, and these proteins package the full-length genomic mRNA into virions to complete the virus life cycle. Retroviral vectors are retroviruses engineered to transfer and integrate specific DNA sequences into the genomes of target cells, and are often designed to be replication-defective to avoid further spread after the initial transfer event. Gene transfer and expression by a replication-defective retroviral vector is referred to as transduction to differentiate this process from infection by a typical virus that leads to virus production and spread.
Keywords: retroviral vector; lentiviral vector; packaging cells; gene therapy





