BASOLATERAL SORTING OF THE HIV TYPE-2 AND SIV ENVELOPE GLYCOPROTEINS IN POLARIZED EPITHELIAL-CELLS - ROLE OF THE CYTOPLASMIC DOMAIN

In polarized epithelial cell lines, enveloped viruses are directionall y released by asymmetric viral budding at specific plasma membrane dom ains, Previous studies have shown that HIV-1 budding and gp160 express ion occur on basolateral membranes whereas the release of HIV-1 Gag pa rticles, in the absence of the Env glycoproteins, is nonpolarized, We have examined the directional transport and surface expression of HIV- 2 and SIV envelope glycoproteins using vaccinia virus recombinants in Vero C1008 polarized epithelial cells. Analogous to HIV-1 gp160, both HIV-2 and SIV surface glycoproteins mere preferentially directed to ba solateral membranes, Hence basolateral expression appears to be a comm on property of the glycoproteins of primate lentiviruses, To explore t he role of the cytoplasmic domain in directing the HIV-2 and SIV Env g lycoproteins to the basolateral surface, stop codons were introduced t o mimic the natural cytoplasmic truncations observed following repeate d passage of these viruses in culture, These truncated glycoproteins a lso were sorted to the basolateral domain, but at a lower efficiency t han the full-length protein product, In contrast, when the entire cyto plasmic domain of the SIV Env glycoprotein was deleted, the tailless S IV mutant was preferentially expressed on the apical surface, These da ta indicate the presence of a basolateral sorting signal in the cytopl asmic domain of primate lentiviral glycoproteins.