FIG. 5.

Analysis of viral protein expression as a marker for reactivation and virus spread in vivo following hyperthermic stress and in vitro following explant into culture. Shown are micrographs of whole ganglia stained immunohistochemically for viral proteins at 48 h post-in vivo hyperthermic stress (A and B), explanted into culture (C1 and C2, 36 h; D, 48 h; E, 72 h), or explanted into culture in the presence of acyclovir (ACV) (G). Most ganglia subjected to in vivo hyperthermic stress were negative at 48 h poststress (A), but 20% of the ganglia tested contained one or more positive neurons that frequently showed signs of degeneration and fragmentation (B and insets). All of the explanted ganglia at 48 and 72 h postexplant contained immunoreactive regions resembling three-dimensional plaques with many clusters of positive cells (D and E). When acyclovir was added to similar cultures, positive neurons were detected, but viral protein was restricted to individual neurons (F, 72 h postexplant; G, 96 h postexplant).