S100B and infection: Furthermore, flow cytometric analysis 96 h after infection showed similar percentages of T-cells expressing GFP from the nef locus (0.7–0.9% GFP-positive cells, Fig. 3) for infected cultures from both species, and DNA extracts from samples taken at the same time point contained comparable levels of 2-LTR circles (0.53–0.81 copies per ng of DNA; Fig. 3).