CD8 T cells clear virus both by perforin-mediated mechanisms
and through the actions of IFN-. Perforin-mediated
cytolysis has been shown to play a role in controlling virus
replication in astrocytes and microglia during acute infection,
while IFN- is necessary for clearance from oligodendrocytes
(14, 22). The mechanism of clearance from neurons has not yet
been addressed. Mice deficient in either perforin or IFN-
experience delayed clearance of MHV in the CNS (14, 22);
however, IFN- is believed to play a more important role in
viral clearance and protection from disease (16).