Envelope glycoprotein and CD4 independence of vpu-facilitated human immunodeficiency virus type 1 capsid export.

The effect of vpu on the release of human immunodeficiency type 1 capsid proteins was examined in the presence or absence of virus-encoded envelope glycoproteins as well as in cells which constitutively express either the CD4 or CD8 protein. The results show that vpu-mediated facilitated export of capsid proteins from HeLa cells does not require expression of the envelope glycoprotein. The experiments also show that export of virus capsid proteins from HeLa cells facilitated by vpu is not affected by coexpression of either the CD4 or CD8 protein. The vpu protein acts in trans to facilitate export of virus capsid proteins from HeLa cells.