Extended Data Figure 6: Low levels of caspase 3 activation in HIV-infected lymphoid CD4 T-cell cultures.

Although the endogenous levels of pro-caspase 3 and pro-caspase 1 expression are similar in lymphoid CD4 T cells, caspase 3 activation in these cells was markedly less abundant after infection with HIV-1, compared to caspase 1. These data are in accord with our findings using fluorescently labelled inhibitor of caspases (FLICA) probes in cultures infected with a GFP reporter HIV-1. In these cultures, the majority of CD4 T cells were abortively infected and showed activation of intracellular caspase 1. No caspase 1 activity was observed in productively infected cells (Fig. 1b). In sharp contrast, caspase 3 activity in these cultures was markedly less abundant, and specifically occurred in productively infected, but not in non-productively infected cells (Fig. 1c). These data are the representative results of three independent experiments performed in tonsillar CD4 T cells isolated from three different donors.