Bak and Bax function to limit adenovirus replication through apoptosis induction.

Area of Science:

• Virology
• Cellular Biology
• Immunology

Background:

• Adenovirus infection induces cell proliferation and apoptosis.
• The adenovirus Bcl-2 homologue E1B 19K inhibits apoptosis.
• The precise mechanism of apoptosis induction and its role in productive infection remain unclear.

Purpose of the Study:

• To elucidate the mechanism by which adenovirus induces apoptosis.
• To investigate the role of Bax and Bak proteins in adenovirus-induced apoptosis and viral replication.
• To understand how the adenovirus E1B 19K protein interferes with apoptotic pathways.

Main Methods:

• Utilized wild-type and E1B 19K mutant adenovirus strains.
• Infected wild-type, Bax-deficient, Bak-deficient, and Bax/Bak-double-deficient baby mouse kidney cells.
• Assessed apoptosis induction, Bid cleavage, Bak/Bax conformation changes, Bak-Bax interaction, caspase activation, E1A expression, and viral replication.

Main Results:

• E1B 19K binds Bak, inhibiting Bak-Bax interaction and Bax conformational changes, thereby blocking apoptosis.
• Infection with E1B 19K mutant viruses induced apoptosis via Bak and Bax, independent of Bid cleavage.
• Bax and Bak deficiency led to increased E1A expression and viral replication, indicating apoptosis limits viral spread.

Conclusions:

• Bax and Bak-mediated apoptosis constitutes a critical cellular antiviral response against adenovirus.
• Adenovirus E1B 19K protein actively suppresses this antiviral mechanism to facilitate viral replication.
• Targeting apoptosis pathways is crucial for understanding and potentially controlling adenovirus infections.