FIG 2.

Probable contamination resulting from two-step culture assay. Mice latently infected with McKrae were subjected to hyperthermic stress to induce HSV reactivation. At 24 h phs, brain stems were harvested and processed by the two-step culture assay as described in Materials and Methods. During the first 3 days of plating, a viral CPE was observed in 2/60 samples (red “X”). All wells were harvested and replated. After 3 additional days of incubation, an additional six positive samples were detected (blue “X”). (A and B) Locations of positive wells during the first plating and spatial relation of additional positive wells after replating. (C) Eight of the six-well plates did not contain positive samples at any time during the two-step assay.