Roberta
Lynn DeBiasi, MD
email: roberta.debiasi@uchsc.edu
REOVIRUS 8B INDUCES MYOCARDITIS BY APOPTOSIS AND
CALPAIN INHIBITOR CX295 IS PROTECTIVE
RL DeBiasi1 B Sherry6 and KLTyler2-5
Depts. Pediatric Infectious Diseases1, Neurology2, Medicine3, Microbiology4, and Immunology5, Univ. of CO Health Sciences Center, Denver, CO and Dept. Microbiology, Pathology and Parisitology, College of Vet. Med., NC State Univ., Raleigh, NC6
Infection of neonatal mice with reovirus strain
8B produces myocarditis in neonatal mice due to a direct viral injury of
myocytes. We now show that this
myocardial injury is due to apoptosis. Apoptosis was verified by TUNEL staining
colocalizing to areas of viral antigen, as well as by demonstration of
characteristic oligonucleotide laddering of nuclear DNA. Having shown that
calpain inhibitors block reovirus-induced apoptosis in vitro, we wished to see
if they would block 8B-induced cardiac injury.
We used Z-leu-aminobutyric acid-CONH(CH2) 3-morpholine (CTX295), a dipeptide
alpha-ketoamide compound which inhibits calpain at the active site to
investigate this question. 2 day old
Swiss-Webster mice were intramuscularly inoculated with 1000 pfu of 8B
reovirus. Drug-treated mice received
daily intraperitoneal (70 mg/kg) injections of CX295 on days 0-5 post-infection,
whereas control mice received daily injections of saline vehicle. At 7 days
post-infection, hearts were examined for histological evidence of
myocarditis. Vehicle-treated mice had
significant myocardial injury whereas heart lesion scores were dramatically
decreased in drug-treated animals. TUNEL and viral antigen staining were also
significantly decreased in myocardium from these animals. Heart and limb virus titers were compared
and revealed a slight decrement in drug-treated animals. This data supports the
notion that calpain inhibitors may be useful in vivo to block apoptotic
injury. Targeting of apoptotic
signaling pathways may serve as a novel antiviral strategy.
