pseudotyped with filovirus GP. The pseudotype virus relies on a recombinant virus that contains a reporter gene instead of the viral envelope protein gene responsible for receptor-binding and membrane fusion. Since filovirus glycoprotein is efficiently incorporated into VSV particles, a recombinant VSV that contains the green fluorescent protein (GFP) gene, instead of the G protein gene can be generated. This virus is not infectious unless the envelope protein responsible for receptor binding and membrane fusion is provided in trans.