The mechanism by which lentivirus envelope (Env) glycoproteins are packaged into budding virions is poorly understood. Simian immunodeficiency virus (SIV) contains an Env protein with an unusually long cytoplasmic tail. To investigate the role of this domain in the incorporation of the SIV Env into virions, we generated a series of SIV Env mutants carrying small in-frame deletions within the cytoplasmic domain. The effects of these mutations on Env synthesis, processing, and association with Gag particles were analyzed by means of the vaccinia virus expression system. All of the mutant Env glycoproteins were synthesized and processed in a manner similar to that of the wild-type Env. However, deletions affecting domains C-terminal to residue 832 in the SIV Env protein significantly impaired Env incorporation into particles. Cell surface biotinylation assays showed that this phenotype could not be attributed to inefficient cell surface expression of the Env mutants. Furthermore, when the Env deletion mutants were tested for their ability to mediate virus entry in single-cycle infectivity assays, those mutations that impaired Env incorporation also caused a severe defect in virus infectivity. Our results suggest that domains in the C-terminal third of the SIV Env protein are required for Env incorporation into particles and Env-mediated virus entry.
|Number of pages||9|
|Publication status||Published - 10 May 2001|
Bibliographical noteFunding Information:
This work was supported by Grant A-13532/98 from Fundación An-torchas (Argentina) to S.A.G. and AIDS Fogarty International Research Collaboration Award AIDS-FIRCA R03 TW00947. This work was facilitated by the resources of the UAB Center for AIDS Research Central Virus Culture Core Facility, funded by NIH CFAR Grant P30-27767. C.C.P.C. is Postgraduate Fellow of the National Research Council of Argentina (CONICET). J.M.M. is supported by Grant A-13532/98 from Fundación Antorchas. J.L.A. and S.A.G. are Career Investigators of the National Research Council of Argentina (CONICET).