The R2 region of pUL37 is essential for invasion of all retrograde circuitry.

<p><b>(A)</b> Diagram of four neuronal circuits exploited by PRV as retrograde transport routes into the rat nervous system. These circuits were each examined following injection of PRV strains encoding a fluorescent capsid reporter into the anterior chamber of the eye. Sensory (trigeminal ganglion), sympathetic (superior cervical ganglion), and parasympathetic (Edinger-Westphal nucleus) circuitry is susceptible to infections following exposure of the cornea, iris, and ciliary body to virus. In addition, motor neurons (oculomotor nucleus) are susceptible to infections resulting from exposure of the extraocular muscles to virus leaked on to the surface of the eye. The parasympathetic circuit includes the ciliary ganglion, which was not examined directly as part of this study but is a mandatory intermediate to observe virus in the Edinger-Westphal nucleus. <b>(B)</b> Representative images of indicated tissues at 48 hpi (scale bars = 250 μm). <b>(C)</b> Summary of wild-type (WT) and R2-mutant (R2) PRV infection data. Fluorescent cells were counted in each indicated neural tissue (n, number of animals examined; n.d. not determined; values are expressed as mean ± s.e.m.). Cells in the iris were not counted, but infection with the WT (+++) consistently exceeded that of R2 (+).</p>