Transmissible gastroenteritis coronavirus induces programmed cell death in infected cells through a caspase-dependent pathway

Area of Science:

• Veterinary Virology
• Cell Biology
• Molecular Virology

Background:

• Porcine transmissible gastroenteritis virus (TGEV) is a significant pathogen in swine.
• Apoptosis, or programmed cell death, is a critical cellular process.
• Understanding TGEV's interaction with host cell death pathways is crucial for disease management.

Purpose of the Study:

• To investigate the induction of apoptosis in TGEV-infected cell lines.
• To elucidate the mechanisms underlying TGEV-induced apoptosis.
• To determine the role of NF-kappaB in this process.

Main Methods:

• Infection of ST cells with TGEV.
• Kinetic analysis of DNA cleavage using agarose gel electrophoresis and flow cytometry.
• Monitoring of mitochondrial transmembrane potential.
• Microscopic observation of cellular morphology.
• Inhibition studies using caspase inhibitors and thiol agents.
• Analysis of NF-kappaB activation via DNA binding assays and decoy experiments.

Main Results:

• TGEV infection induced apoptosis in ST cells, with initial signs appearing 10-12 hours post-infection.
• Apoptosis preceded observable morphological changes.
• The caspase inhibitor blocked TGEV-induced apoptosis without affecting viral production.
• Pyrrolidine dithiocarbamate inhibited apoptosis, suggesting a role for oxidative stress.
• NF-kappaB DNA binding was rapidly induced by TGEV, but NF-kappaB activation was not essential for TGEV-induced apoptosis.

Conclusions:

• TGEV infection triggers apoptosis in susceptible cells.
• The induction of apoptosis appears to be mediated by cellular oxidative stress.
• NF-kappaB activation is not a critical factor in TGEV-induced programmed cell death.