Lipid rafts and HIV-1: from viral entry to assembly of progeny virions

Background: Lipid rafts are currently an intensely investigated topic of ce ll biology. In addition to a demonstrated role in signal transduction. of t he host cell, lipid rafts serve as entry and exit sites for microbial patho gens and toxins, such as FimH-expressing enterobacteria, influenza virus, m easles virus and cholera toxin. Furthermore, caveolae, a specialised form o f lipid raft, are required for the conversion of the non-pathogenic prion p rotein to the pathogenic scrapie isoform. Objectives: A number of reports h ave shown, directly or indirectly, that lipid rafts are important at variou s stages of the human immunodeficiency virus type-1 (HIV-1) replication cyc le. The purpose of this paper is to provide a brief overview of the role of membrane-associated lipid rafts in cell biology, and to evaluate how HIV-1 has hijacked this cellular component to support HIV-1 replication. Special sections are devoted to discussing the role of lipid rafts in (1) the entr y of HIV-1, (2) signal transduction regulation in HIV-1-infected cells, (3) the trafficking of HIV-1 proteins via lipid rafts during HIV-1 assembly; a nd a further section discusses the role of cholesterol in mature HIV-1. Sum mary: Like a number of other pathogens, HIV-1 has evolved to rely on the ho st cell lipid rafts to support its propagation during multiple stages of th e HIV-1 replication cycle. This review has highlighted the importance of li pid rafts in HIV-1 replication. (C) 2001 Elsevier Science BY. All rights re served.