FUNCTIONAL RT AND IN INCORPORATED INTO HIV-1 PARTICLES INDEPENDENTLY OF THE GAG POL PRECURSOR PROTEIN/

The expression and incorporation of retroviral enzymes into virions in the form of Gag/Pol precursor polyproteins is believed to be importan t for the assembly of infectious viral particles, HIV-1 encodes a 160 kDa Gag/Pol precursor that includes Gag, protease (PR), reverse transc riptase (RT) and integrase (IN), We have developed the use of HIV acce ssory proteins (Vpr and Vpx) as vehicles to incorporate protein of bot h viral and non-viral origin into virions by expression in trans as he terologous fusion proteins (Wu et al., 1995, 1996a), To analyze the ro le of Gag/Pol in the formation of infectious virions, we incorporated RT and IN into HIV-1 particles in trans, as fusion partners of viral p rotein R (Vpr). Virions derived from an RT and IN minus proviral clone were infectious and replicated through a complete cycle of infection when RT and IN proteins were provided in trans, These results demonstr ate that functional RT and IN proteins can be provided in trans, and t hat their expression and incorporation into virions as components of G ag/Pol are not required for the formation of infectious virions, Thus, for the first time, we have demonstrated for a human pathogenic retro virus that processes of assembly and the function of critical viral en zymes can be unlinked, This finding will provide unique opportunities to explore retroviral RT/IV function and the role of Gag/Pol in the fo rmation of infectious virions in the context of a replicating virus (i n vivo).