Delivering biologically relevant nucleic acids and proteins to appropriate cells of multicellular organisms for the purposes of genetically modifying either somatic or germline genomes is a central problem for not only insect biologists but for those working on other organisms including developers of gene therapies.
The technical developments associated with human gene therapies could have applications in some insect systems.
Lentiviruses are popular platforms for genetically modifying human cells. Might they have an application in insects?
He et al (2014) describe their efforts to use lentiviruses to deliver a meganuclease to human cells in culture.
Lentiviruses, like other vectors, are usually used to deliver transgenes that need to be expressed in order to affect the phenotype of the target cells. He et al (2014) use a lentivirus to deliver a monomeric version of the I-CreI meganuclease modified to recognize a specific sequence on the Chromosome 14.
I-CreI and other meganucleases have been used in insects and there are now other programmable endonucleases available as well. What was ‘special’ about the I-CreI used by He et al (2014) is that it was monomeric – which makes delivery easier. Normally it acts as a dimer.
What is particularly interesting about the work of He et al (2014) is their loading lentivirus particles with a ‘therapeutic’ protein.
The motivation for using lentivirues to deliver protein instead of a transgene in this case was the potential toxicity associated with overexpressing endonucleases that can arise from transgene expression. The idea is that meganuclease protein will persist for a shorter period of time and reduce the toxic affects seen associated with high concentrations these enzymes
Lentiviral protein delivery of meganucleases in human cells mediates gene targeting and alleviates toxicity 2014 C He, A Gouble, A Bourdel, V Manchev, L Poirot, F Paques, P Duchateau, A Edelman and O Dano
Gene Therapy , (12 June 2014) | doi:10.1038/gt.2014.51