MURINE RETROVIRAL VECTOR THAT INDUCES LONG-TERM EXPRESSION OF HIV-1 ENVELOPE PROTEIN

A retroviral vector was constructed that induces long-term expression of human immunodeficiency virus type 1 (HIV-1) rev, vpu and env genes. The vector contains the neo gene and a cytomegalovirus (CMV) immediat e early promoter followed by HIV-1 sequence. When HeLa cells were infe cted with viral stocks derived from this vector, about 25% of the resu lting G418-resistant clones expressed HIV-1 envelope protein (Env), ea sily detectable by Western blot analysis, metabolic labelling, and syn cytium formation after co-cultivation with HeLa-CD4 cells. In most cas es the level of Env expression was higher than in a T cell line (H9) c hronically infected with HIV-1. Env-expressing HeLa cell lines also ex pressed Rev, detected by transfection with a Rev-dependent CAT gene co nstruct, and Vpu, detected by immunoprecipitation with a Vpu-specific antiserum. The 75% of G418-resistant HeLa cell lines that did not expr ess Env were found to contain proviruses that had undergone deletion o f env sequences corresponding to a known intron; presumably these cell lines arose as a result of infection with virions derived from splice d RNAs. This vector should be useful for studying non-transient effect s of HIV Env, Rev and Vpu in tissue culture, and for the production of Env- and/or Rev-expressing cell lines.