The envelope (Env) protein of many retroviruses, including ALV,
determines the capacity of the virus to produce cytopathic effect
(CPE) (Dorner and Coffin, 1986; Riedel et al., 1988; Siliciano, 1996).
This suggests that the envelope protein which functions in cell
attachment and fusion-mediated entry, may directly contribute to cell
killing. Clues about mechanisms by which the ALV Env protein
contributes to cell death were obtained following identification of the
cellular receptor for cytopathic ALV strains ALV-B and ALV-D by
expression cloning methods (Brojatsch et al., 1996). Mouse cells that
usually do not support infection by ALV were rendered permissive by