Fig. 2.

Patterns of spread of VSV vectors injected into the eye and brain. (A) Retrograde transport of VSV was tested for VSV(RABV-G), WT VSV (which uses VSV-G), and VSV(LCMV-G) after injection into the LGN. The number of fluorescently labeled RGCs per retina at 4 dpi was counted (n = 4 animals for each virus). (Error bars: 1 SD.) (B) Anterograde transmission was tested by injection into the vitreous body of the eye. To determine whether RGCs were infected, RGC axons were examined and found to be fluorescently labeled after viral injection, as shown by an image taken at the optic nerve head of a VSV(LCMV-G)-infected retina 4 dpi. (C) An anterograde transsynaptic virus injected into the retina would be expected to label several brain centers involved in visual processing by anterograde spread, including the hypothalamus (h), LGN (L), SC (s), and V1 (v). Red arrows show direct targets of RGCs; blue indicates an indirect target; green indicates the injection site. (D–F) Parasaggital sections from brains after VSV(LCMV-G) injection into the eye. (D and E) In all mice injected in the eye subretinally, labeling in the brain was restricted to the visual system. At 7 dpi, strong labeling was observed in the deep layers of the SC (white arrow in D; high magnification shown in E). (F) A parasaggital section of the SC showing labeling in the more superficial layers (white arrowhead) and in the deeper layers (yellow arrowheads) at 6 dpi. Labeling was seen initially in the more superficial layers at 3 dpi and then in deeper layers at later times. (G–I) Primary retinorecipient areas (LGN, SC, SCN) and secondary (V1) visual centers were labeled after infection of the eye by VSV(LCMV-G), but not by the other viruses. Labeled nuclei 4 dpi included the LGN (G), SC (H), and V1 (I). (Images are from the same brain.) C is adapted from Franklin & Paxinos (56).