Avian sarcoma leukosis virus receptor-envelope system for simultaneous dissection of multiple neural circuits in mammalian brain

Genetic dissection of multiple neural pathways remains challenging because of the limited number of genetic methods that can be used simultaneously. To overcome this limitation, we used modified avian sarcoma and leukosis virus envelopes and receptors to develop highly orthogonal genetic tools that can achieve expression of different genes in different target cells. From in vitro and in vivo screens, we identified tools that can specifically transfer genes of interest into mammalian neurons via engineered receptors, with minimal unintended interactions. Using this approach, we achieved pathway-specific, differential fluorescent labeling of three thalamic neuronal populations, each projecting into different cortical regions. Thus, our approach provides independent, simultaneous, and specific genetic tools for manipulating intermingled neural pathways in vivo.