A Plasma Membrane Localization Signal in the HIV-1 Envelope Cytoplasmic Domain Prevents Localization at Sites of Vesicular Stomatitis Virus Budding and Incorporation into VSV Virions

AbstractPrevious studies showed that the HIV-1 envelope (Env) protein was not incorporated into vesicular stomatitis virus (VSV) virions unless its cytoplasmic tail was replaced with that of the VSV glycoprotein (G). To determine whether the G tail provided a positive incorporation signal for Env, or if sequences in the Env tail prevented incorporation, we generated mutants of Env with its 150-amino-acid tail shortened to 29, 10, or 3 amino acids (Envtr mutants). Cells infected with VSV recombinants expressing these proteins or an Env-G tail hybrid showed similar amounts of Env protein at the surface. The Env-G tail hybrid or the Envtr3 mutant were incorporated at the highest levels into budding VSV virions. In contrast, the Envtr29 or Envtr10 mutants were incorporated poorly. These results defined a signal preventing incorporation within the 10 membrane-proximal amino acids of the Env tail. Confocal microscopy revealed that this signal functioned by causing localization of human immunodeficiency virus type 1 Env to plasma membrane domains distinct from the VSV budding sites, where VSV proteins were concentrated

Replication of Primary HIV-1 Isolates Is Inhibited in PM1 Cells Expressing sCD4-KDEL

AbstractExpression of a soluble CD4 molecule (sCD4-KDEL) containing a specific retention signal for the endoplasmic reticulum was shown previously to block propagation of the HIV-1MNprototype strain in a transformed T cell line. However, the virus present in HIV-1-infected individuals is more closely represented by primary HIV-1 isolates which, unlike the HIV-1MNstrain, have not been adapted to growth in cell lines. To determine if sCD4-KDEL could block replication of primary isolates we used the PM1 cell line that has been shown to propagate primary isolates without adaptation. Here we show that the replication of four primary HIV-1 isolates was strongly inhibited in PM1 cells that expressed sCD4-KDEL under control of the HIV-1 LTR. Infection with primary HIV-1 isolates induced sCD4-KDEL expression driven by the LTR, HIV-1 spread was dramatically reduced, and reverse transcriptase activity in the cell culture supernatants was greatly diminished. sCD4-KDEL, therefore, represents a potent inhibitor of HIV-1 replication for gene therapy-based approaches for the treatment of AIDS