Fig. 1

Schematic diagram of preparation of PRV tracers. (A). The PRV292 was prepared by means of homologous recombination between PS292 and the genome of PRV Bartha strain, which was used for preparing the PRV676 and PRV829 tracers. The TK gene was deleted from the genome of PRV292. The PRV676 and PRV829 were generated by using the strategy in (B) and (C), respectively. Briefly, the PS676 and PS829 were separately tranfected into BHK-21 cells, and then the PRV292 was added into the wells. If the Cre was present in neurons, the fluoresent protein and the TK protein were expressed, and then the progeny viruses were produced