
<ArticleTitle><prot>Gag</prot>-<prot>Pol</prot> supplied in trans is efficiently packaged and supports viral function in human immunodeficiency virus type 1.</ArticleTitle>
<AbstractText>The intracellular trafficking and subsequent incorporation of <prot>Gag</prot>-<prot>Pol</prot> into human immunodeficiency virus type 1 (HIV-1) remains poorly defined. <prot>Gag</prot>-<prot>Pol</prot> is encoded by the same mRNA as <prot>Gag</prot> and is generated by ribosomal frameshifting. The multimerization of <prot>Gag</prot> and <prot>Gag</prot>-<prot>Pol</prot> is an essential step in the formation of infectious viral particles. In this study, we examined whether the interaction between <prot>Gag</prot> and <prot>Gag</prot>-<prot>Pol</prot> is initiated during protein translation in order to facilitate the trafficking and subsequent packaging of <prot>Gag</prot>-<prot>Pol</prot> into the virion. A conditional cotransfection system was developed in which virion formation required the coexpression of two HIV-1-based plasmids, one that produces both <prot>Gag</prot> and <prot>Gag</prot>-<prot>Pol</prot> and one that only produces <prot>Gag</prot>-<prot>Pol</prot>. The <prot>Gag</prot>-<prot>Pol</prot> proteins were either immunotagged with a His epitope or functionally tagged with a mutation (K65R) in reverse transcriptase that is associated with drug resistance. <prot>Gag</prot>-<prot>Pol</prot> packaging was assessed to determine whether the <prot>Gag</prot>-<prot>Pol</prot> incorporated into the virion was preferentially packaged from the plasmid that expressed both <prot>Gag</prot> and <prot>Gag</prot>-<prot>Pol</prot> or whether it could be packaged from either plasmid. Our data show that translation of <prot>Gag</prot> and <prot>Gag</prot>-<prot>Pol</prot> from the same mRNA is not critical for virion packaging of the <prot>Gag</prot>-<prot>Pol</prot> polyprotein or for viral function.</AbstractText>
