microinjection of xenopus laevis oocytes as a system for studying nuclear transport of viruses microinjection of xenopus laevis oocytes is an excellent system for studying nuclear transport because of the large size of the oocyte and its high nuclear pore complex npc density in addition the fact that xenopus oocytes are not permissive for most mammalian viruses makes this system especially useful for studying nuclear transport of viruses in the absence of the confounding factor of virus replication in this article we briefly discuss the contribution of microinjection of xenopus oocytes to the field of nuclear transport we then describe the protocols we have developed using microinjection of xenopus oocytes to study nuclear transport of viral capsids and summarize variations of the technique that can be used to address many different questions about the nuclear transport of viruses