Our piggyBac vector system is highly effective for inserting foreign DNA into the host genome of mammalian cells. This system is technically simple, utilizing plasmid transfection (rather than viral transduction) to permanently integrate your gene(s) of interest into the host genome.

The system is derived from the piggyBac transposon, which is originally isolated from the cabbage looper (Trichoplusia ni; a moth species). Based on sequence homology, the piggyBac transposon was found to belong to a class of transposons common to many animals.

The piggyBac system contains two vectors, both engineered as E. coli plasmids. One vector, referred to as the helper PBase plasmid, encodes the transposase. The other vector, referred to as the transposon plasmid, contains two terminal repeats (TRs) bracketing the region to be transposed. The gene to be delivered into host cells is cloned into this region.

When the PBase vector and the piggyBac transposon vector are co-transfected into target cells, the transposase produced from the helper would recognize the two TRs on the transposon, and insert the flanked region including the two TRs into the host genome. Insertion typically occurs at host chromosomal sites that contain the TTAA sequence, which is duplicated on the two flanks of the integrated fragment.

PiggyBac is a class II transposon, meaning that it moves in a cut-and-paste manner, hopping from place to place without leaving copies behind. (In contrast, class I transposons move in a copy-and-paste manner.) Because the helper plasmid is only transiently transfected into host cells, it will get lost over time. With the loss of the helper plasmid, the integration of the transposon in the genome of host cells becomes permanent. If these cells are transfected with the helper plasmid again, the transposon could get excised from the genome of some cells, footprint free.

Highlights of our vector

Our piggyBac plasmid along with the helper PBase plasmid are optimized for high copy number replication in E. coli, efficient transfection into a wide range of target cells, and high-level expression of the transgene carried on the vector.

Advantages

Permanent integration of vector DNA: Conventional transfection results in almost entirely transient delivery of DNA into host cells due to the loss of DNA over time. This problem is especially prominent in rapidly dividing cells. In contrast, transfection of mammalian cells with the piggyBac transposon plasmid along with the helper plasmid can deliver genes carried on the transposon permanently into host cells due to the integration of the transposon into the host genome.

Technical simplicity: Delivering plasmid vectors into cells by conventional transfection is technically straightforward, and far easier than virus-based vectors which require the packaging of live virus.

Very large cargo space: Our transposon vector can accommodate ~30 kb of total DNA. The plasmid backbone and transposon-related sequences only occupies about 3 kb, leaving plenty of room to accommodate the user's sequence of interest.

Disadvantages

Limited cell type range: The delivery of piggyBac vectors into cells relies on transfection. The efficiency of transfection can vary greatly from cell type to cell type. Non-dividing cells are often more difficult to transfect than dividing cells, and primary cells are often harder to transfect than immortalized cell lines. Some important cell types, such as neurons and pancreatic β cells, are notoriously difficult to transfect. Additionally, plasmid transfection is largely limited to in vitro applications and rarely used in vivo. These issues limit the use of the piggyBac system.

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