Expression of more than two proteins is theoretically possible from the use of multiple IRES elements, but such an approach may be better suited for replication-competent, packaging defective, replicon vectors with their greater capacity (at least 5 kb) for insertion of heterologous sequences [2].
Therefore cells used to make RVF-VLPs in the absence of replication (e.g. –N and –RdRp) contain genomic RNA (synthesized by T7 RNA polymerase) that is competent for packaging.
We generated GFP-expressing LVs with either integrase-defective (IDLV) or integrase-competent (ICLV) packaging constructs and compared their transduction efficiency and transgene expression levels in human cell lines and primary hepatocytes in vitro.
Instead, the company packaged a competent system into a package the size of an Xbox One.
Replication and packaging competent alphavirus vectors have been developed by duplicating the subgenomic RNA promoter element in the genome [2], [3].
Interestingly, the results reported here may also prove to be beneficial in addressing the second problem commonly associated with replication and packaging competent alphavirus vectors, instability.
Replication and packaging competent vectors developed from alphavirus genomes have proven to be useful in applications ranging from studies of basic virology to vaccine development [2], [26], [27], [28], [29].
That morality play aside, the Optima is a competent and extremely pleasant package, with style and price at the core of its allure.
We assume that only the positive-sense replication-competent form is packaged (Ansardi et al., 1996, but see; Liu et al., 2010), and that, following Nugent et al. (1999), genomes can only be packaged as they are synthesized from a negative-sense strand.
Our results explain why certain pRNA mutants are inactive in DNA packaging while remaining competent in procapsid binding, since the mutations were located in a domain involved in DNA translocation that is dispensable for procapsid binding.
For practical reasons, most pharmacometricians are competent in only one or two packages.
