Figure 3

Explant and In vivo reactivation in Swiss Webster mice latently infected with R-13 and N-7. R-13 and N-7 were compared for reactivation from latency (>40 days pi) using in vitro and in vivo reactivation assays. (A) In a standard TG explant assay, no difference between R-13 and N-7 reactivation frequency was observed (p = 0.99, Student’s t test) although the difference between virus recovered at time 0 and 3 days post explant was significant in both groups (p = 0.0003, ANOVA). (B) The in vivo reactivation frequency (percentage of mice with infectious virus detected in TG) was also not different between R-13 and N-7 at 22 hrs. post hyperthermic stress (Student’s t test, expt. 1 p = 0.89, expt. 2 p = 0.83) and (C) the number of neurons exiting latency was also not different (expt. 1 p = 0.39, expt. 2 p = 0.86). Latently infected TG were subjected to whole ganglion immunohistochemistry to detect viral protein at 0 hrs. (D), and 3 days (E) post explant. Viral protein-expressing neurons (black arrows) and tracts (white arrowheads) mark the range of viral spread. Viral protein-expressing neurons (black arrows) are detectable in TG from N-7 (F) and R-13 (G), which reactivated from latently infected TG, at 22 hrs. after hyperthermic stress in vivo.