The present invention provides a conditionally replicating viral vector,methods of making, modifying, propagating and selectively packaging, and usingsuch a vector, isolated molecules of specified nucleotide and amino acidsequences relevant to such vectors, a pharmaceutical composition and a hostcell comprising such a vector, the use of such a host cell to screen drugs.The methods include the prophylactic and therapeutic treatment of viralinfection, in particular HIV infection, and, thus, are also directed to viralvaccines and the treatment of cancer, in particular cancer of viral etiology.Other methods include the use of such conditionally replicating viral vectorsin gene therapy and other applications.
