When the tropism of the virus was examined at one month post-infection by co-staining for LCMV and GFAP (astrocytes) or NeuN (neurons), it was revealed that all of the parenchymal LCMV staining overlapped with GFAP (Fig. 2) not NeuN (data not shown), supporting the notion that astrocytes are the preferred parenchymal target for clone 13 introduced intravenously. This evidence concerns the gene GFAP and infection.