FIG. 3.

The extents of retrograde transsynaptic infection of the forebrain produced by injection of PRV mutants into the wall of the stomach are illustrated. Low-power, negative images, where circumscribed areas of viral immunoreactivity are revealed as a white signal on a dark background, are shown. Vertical columns illustrate selected coronal-plane sections obtained at the levels of B (right column) and C (left column) illustrated in Fig. 1. Horizontal rows illustrate the pattern of infection produced by PRV-25, PRV-26, PRV-91, and PRV-Bartha (PRV-Ba) 96 h following stomach inoculation. Animals injected with PRV-Becker did not survive that long and could not be analyzed. The most-extensive infection is produced by PRV-Ba. The other mutants infect a subset of the neurons infected by PRV-Ba. IC, insular cortex.