Host factors in virus budding ? Insights from yeast

Abstract

The budding yeast, Saccharomyces cerevisiae, is an excellentmodel organism for the study of eukaryotic cellular processes such as endocytosis 1. Like other eukaryotic cells, yeast take up extracellular material by invagination of the plasma membraneto form a vesicle. The internalised material is transported to a membrane-bound compartment, the early endosome. As the early endosome matures, internal vesicles form within the lumen giving it the appearance of a multivesicular body (vesicles enclosed by a membrane). The machinery required for endosome maturation is highly conserved between yeast and mammalian cells. In mammalian cells this machinery is also required for the budding of enveloped viruses. Here we discuss how studies of endosome maturation in S. cerevisiae have given valuable insights into the mechanism by which clinically important enveloped viruses, including human immunodeficiency virus (HIV) and hepatitis B virus, are released from mammalian cells.