Activation of host caspases by virus

Apoptosis (or programmed cell death) is a controlled process leading to cell death characterized by chromatin condensation, DNA fragmentation, cell shrinkage, and compartimentalization of the dead cells to apoptotic bodies. The host immune system uses apoptosis to eliminate cells infected by pathogens. Apoptosis of infected cells is caused either by cytolytic cells activated during the anti-viral response, or directly by viral infection. Host caspases, constitute an evolutionary conserved family of aspartate-specific cysteine proteases that are at the heart of the apoptotic machinery.

HBX HIVprot NS3 E2 TNF TNFR TRADD FADD CASP8 CASP8 CASP8 FLIP CASP3 CASP3
Viruses from several different families are able to exploit their host's cell death programmes so as to maximize viral fitness. Apoptosis activation via caspases offers several advantages for viruses. Indeed, it may facilitate progeny virion release after host cell death. Furthermore, during apoptosis, the entire content of the cell, including virions are packaged into membrane-bound apoptotic bodies that are taken by surrounding cells. This process limits the inflammatory response and allow viruses to spread without being detected. HIV protease directly cleaves procaspase-8 to promote apoptosis. HPV 18 E2 protein induces oligomerization of caspase 8 through direct interaction.