Assays to assess arenaviral glycoprotein function

Arenaviruses, such as Lassa virus (LASV) and Pichindé virus (PICV), are enveloped viruses with a bi-segmented ambisense RNA genome. The large (L) genomic segment encodes the Z matrix protein and the L RNA-dependent RNA polymerase, whereas the small (S) genomic segment encodes the nucleoprotein (NP) and the glycoprotein precursor complex (GPC). GPC is processed by signal peptidase in the endoplasmic reticulum into the stable signal peptide (SSP) and GP1/GP2, which is further cleaved by the Golgi-resident subtilisin kexin isozyme-1 (SKI-1)/site-1 protease (S1P) into the cellular receptor-recognition subunit GP1 and the transmembrane subunit GP2, which helps promote the membrane fusion reaction to allow virus entry into the cell. This article describes assays to assess PICV GPC expression, proteolytic processing, fusion function, and GPC-mediated virus-like particle (VLP) entry into cells under tissue-culture conditions.