Detection of vesicular stomatitis virus (murine leukemia virus) pseudotypes by immunoelectron microscopy.

Abstract Superinfection of a murine leukemia virus (MuLV)-producing rat bone tumor cell culture with the temperature-labile vesicular stomatitis virus (VSV) mutant tl-17 led to the formation of VSV(MuLV) pseudotype. This pseudotype was conveniently detected by immunoelectron microscopy (IEM) as bullet-shaped VSV particles reacting with anti-MuLV serum. In addition, VSV(MuLV) pseudotype formation was confirmed by results of thermoinactivation and neutralization tests. It is expected that the IEM described herein will find broader application to the demonstration of other pseudotypes that cannot be readily assayed by conventional infectivity assays.