The envelope of the rabies virus (a prototype of the Rhabdoviridae) contains two species of virus-coded major polypeptides; a transmembrane glycoprotein (G) and a matrix protein (M; formerly called M2), and some host-derived minor components including CD44 and a CD99-related glycoprotein (VAP21) (20,36,37,40). The M protein is a small non-glycosylated internal virion protein (Mr.ϭ24 kDa), and is thought to be located underneath the lipid bilayer of the envelope, where the M protein is thought to associate with the viral G protein and also the viral nucleoprotein (RNP) (41).The G protein has been studied extensively for many years because of its possible roles in determining the host range, neurovirulence, and immunogenicity of the virus as well as important roles in the virus replication cycle