Association of Murine Leukemia Virus Pol with Virions, Independent of Gag-Pol Expression

During the replication cycle of murine leukemia virus (MLV), Pol is normally synthesized as part of a Gag-Pol fusion protein. In this study, the ability of free MLV Pol to be incorporated into virions was examined. When MLV Gag and MLV Pol were coexpressed from separate plasmids in cells, reverse transcriptase (RT) activity associated with Gag core particles at a slightly lower level than did RT activity generated from wild-type Gag-Pol expression. Particles produced in this manner were somewhat less infectious than those produced with wild-type Gag-Pol. A smaller amount of MLV Pol also associated with heterologous human immunodeficiency virus type 1 Gag cores.