Caspase-3-dependent reactivation of latent herpes simplex virus type 1 in sensory neuronal cultures.

Life-long latent herpes simplex virus type 1 (HSV-1) is harbored in sensory neurons where sporadic reactivation occurs. Reactivation stimuli may involve activation of apoptotic signaling in the neuron. Previous experiments have demonstrated that reactivation of latent HSV-1 in dorsal root ganglion (DRG) neuronal cultures occurred following nerve growth factor (NGF) deprivation. NGF deprivation stimulates apoptotic signaling by activating the proapoptotic proteolytic enzyme, caspase-3. When DRG neuronal cultures harboring latent HSV-1 were treated with a caspase-3-specific inhibitor, NGF deprivation-induced reactivation was significantly reduced. Interestingly, the caspase-3 inhibitor had no effect on productive HSV-1 infection. Furthermore, activation of caspase-3 with either C2-ceramide or a recombinant adenovirus expressing caspase-3 caused significant HSV-1 reactivation.