Development of cell lines stably expressing human immunodeficiency virus type 1 proteins for studies in encapsidation and gene transfer.

Experiments were done to test cell lines for their capacity to express human immunodeficiency virus type 1 (HIV-1) proteins in a stable manner. Marked differences were seen in the ability to stably express and export viral Gag and Pol proteins. Two cell lines, one suspension (MDS) and one monolayer (SW480), were established which exported these proteins at high level. Two other cell lines, HeLa and THP-1, showed poorer expression and very limited particle release. Single cell cloning was used to select the optimal producing clones from the lines. These produced large quantities of viral core particles pelletable from the supernatants. Cell lines were constructed from these clones which stably expressed in addition either the HIV-1 Envelope or a packageable HIV-based vector. The vector was shown to be packaged within the viral core particles. Transient transfection of envelope expressing constructs into a gag-pol plus vector cell line, or the vector into a gag-pol plus envelope expressing cell line resulted in gene transfer to CD4+ target cells. These cell lines provide useful tools with which to study the assembly and export of viral proteins and RNA, for assay of alternative envelope proteins to pseudotype HIV cores, for assessment of antiviral drugs and as a source of correctly processed proteins for immunological studies.