What is the cloning/packaging capacity of a retroviral vector from Takara Bio?
What is the cloning/packaging capacity of a retroviral vector from Takara Bio?
Wild-type moloney murine leukemia virus (MMLV) contains ~8.2 kb of genome, including both LTRs. Artificially creating a genome larger than 8.2 kb will result in unstable viral particles and a dramatic drop in viral titer. For recombinant retroviruses such as those generated using Retro-X systems, much of the viral genome has been replaced with other useful sequences such as selection markers or fluorescent proteins, but enough space remains for cloning transgenes. Since each pRetro-X and pRetro-Q vector contains different useful sequences, the available space for cloning your transgene varies.
To determine the maximum recommended transgene size, consult your retroviral vector map and determine the position of the end of the 3' LTR (the end of the 5' LTR is always at position 1), then subtract that from 8.2 kb. For example:
-The 3' LTR of pQCXIP ends at 4.3 kb, so ~3.9 kb of space remains for you to clone in your gene.
-The 3' LTR of pRetroX-IRES-ZsGreen1 ends at 3.3 kb, so ~4.9 kb of space remains for you to clone in your gene.