Lack of effect of cytoplasmic tail truncations on human immunodeficiency virus type 2 ROD Env particle release activity

In addition to its role in receptor binding, the envelope glycoprotein of c ertain human immunodeficiency virus type 2 (HIV-2) isolates, including ROD1 0, exhibits a biological activity that enhances the release of HIV-2, HIV-1 , and simian immunodeficiency virus particles from infected cells. The pres ent study aims at better defining the functional domains involved in this b iological activity. To this end, we have characterized the envelope protein of the ROD14 isolate of HIV-2, which, despite 95% homology with the ROD10 envelope at the amino acid level, is unable to enhance viral particle relea se. Site-directed mutagenesis showed that the presence of a truncation in t he cytoplasmic tail of the ROD14 envelope was not responsible for the lack of activity, as previously reported for the HIV-2 ST isolate (G, D, Ritter, Jr,, G, Yamshchikov, S, J, Cohen, and M, J, Mulligan, J, Virol, 70:2669-26 73, 1996), Similarly, several modifications of the length of the ROD10 enve lope cytoplasmic tail did not impair its ability to enhance particle releas e, suggesting that, in the case of the HIV-2 ROD isolate, particle release activity is not regulated by the length of the cytoplasmic tail.