Induction of chromatin condensation and nuclear fragmentation in EHV5 antigen-expressing T lymphocytes (A) and B lymphocytes (B) following inoculation at a MOI of 10. Left panels; the percentage of EHV5-inoculated cells expressing both EHV5 antigens and nuclear fragmentation is indicated by black bars. White bars represent the percentage of inoculated cells that express EHV5 antigens, but show no signs of nuclear fragmentation. Data are represented as mean + SD and were obtained from 3 individual horses. Right panels; representative confocal images of EHV5 expression (Sultan; green) in T and B lymphocytes. Cell nuclei were counterstained with Hoechst 33342 (blue). Note the signs of nuclear fragmentation (i.e. translucent and/or compartmented appearance of cell nuclei, as shown by the translucent and/or punctuated Hoechst signal; white arrows). The scale bars represent 5 µm.