Chimeric CD4 proteins were assembled. They contained the entire CD4 ectodomain that is linked to different membrane anchors. Membrane anchors consisted of either glucosyl phosphatidyl inositol (gpi), the transmembrane and cytoplasmic regions of HIV-1 Env protein, or the vesicular stomatitis virus G glycoprotein, respectively. The HIV-1 co-receptor CXCR4 and CD4 were independently inserted into viral envelopes. We compared the insertion of six different CD4/CXCR4 constructs into HIV-1 envelopes, as well as their functionality in targeting and specific infection of cells that constitutively express the HIV-1 Env protein. All of the six different HIV-1 (CD4/CXCR4) pseudotypes were able to transduce Env (+) cells at similar efficiency. In addition, stable transduction of the Env (+) recipient cells demonstrated that all chimeric proteins were functional as receptors for Env when inserted into HIV-1 envelopes. In fact, these results demonstrate for the first time a stable transduction by a targeted HIV-1 pseudotype virus.