HIV-1 Virus-like Particle Budding Assay

Abstract

Viral replication culminates with the egress of the mature virion from the host cell. This step of the viral life cycle has recently garnered increased attention with the discovery of the cellular restriction factor, Tetherin, which tethers budded virions to the surface of infected cells and inhibits viral spread. The importance of this block in viral infections has been suggested by the discovery of viral antagonists, such as HIV-1 Vpu, which counteract Tetherin. This protocol describes a system to study HIV-1 budding under BSL-2 safety conditions. It takes advantage of the ability of many viral matrix/capsid proteins to generate non-infectious virus-like particles (VLPs) with the expression of a single viral protein (i.e. HIV-1 p24 Gag). This protocol was recently used to characterize the effect of Tetherin isoforms on VLP release in the presence of HIV-1 Vpu (Cocka and Bates, 2012). Simultaneous expression of Tetherin and other viral antagonists can be used to study Tetherin-mediated restriction on viral budding.