Retroviruses are attractive gene-delivery systems because this is how they make a living. What cells a virus will enter are determined by viral proteins on its surface. This determines the tropism of a virus. Different viruses have different tropisms. Many years ago now it became possible to alter the tropisms of some retroviruses so that they would enter any cell they encountered. They were pseutyped viruses and were pantropic.
Some twenty years ago when non-drosophilid insect transformation was largely an unsolved problem there was a fleeting interest in pantropic pseudotyped retroviruses. Significant effort was expended in trying to get these to work as mosquito transformation vectors. While mosquito cells in culture could be transformed using pantropic pseudotyped retroviral vectors, which was significant because it showed the integration machinery was not a limitation, transgenic mosquitoes never emerged from these efforts, unfortunately. The problem seemed to be that viral titers could never be made high enough to introduce more that a few viral particles in the picoliters of liquid injected into early mosquito embryos.
That was discouraging, but fortunately transposon-based systems were soon available.
But transposon-based systems delivered by embryo microinjection are just not going to be feasible for all insects for any number of reasons. There are many more insects and insect research communities where transient- and germ-line gene delivery is now a pressing problem. It might be worth thinking again about pseudotyped retroviruses. They may actually have an important role to play in insects such as aphids and other ‘delivery challenged’ systems.
Mann et al. (2014) describe their efforts to use pseudotyped murine leukemia virus for schistosome transgenesis.
While schistosomes are not insects and present their own set of unique challenges, this paper provides a good example of pushing the envelope of genetic technology and its application to important systems.
Pseudotyped murine leukemia virus for schistosome transgenesis: approaches, methods and perspectives,
Victoria H. Mann, Sutas Suttiprapa, Danielle E. Skinner, Paul J. Brindley, Gabriel Rinaldi
Transgenic Research June 2014, Volume 23, Issue 3, pp 539-556 DOI 10.1007/s11248-013-9779-3