Baculovirus interaction with host apoptotic pathways.

Baculoviruses possess at least two different classes of anti-apoptotic genes which allow them to block apoptosis of their host cells, thereby increasing the infectivity of the virus and extending the range of cells and hosts that can be efficiently infected. One of these genes, p35, encodes a broadly acting inhibitor of the caspase family of cysteine proteases involved in the induction and execution of apoptotic cell death. The other class of genes, the iaps, are found in higher eukaryotes, as well as baculoviruses, and appear to function at an earlier point in the pathway(s) leading to apoptosis. The IAPs appear to have a more limited role, and the action of at least some of these proteins may be confined to a narrower spectrum of signal transduction pathways. Characterization of the iaps has provided insight into the basis of a prominent human genetic disorder. Both classes of baculovirus inhibitors are proving to be useful in unraveling the molecular pathways governing cellular apoptosis.