ABSTRACT
Pseudotypes are virus particles containing the genome of one virus and coat proteins of another. Pseudotypes represent an extreme form of phenotypic mixing, first recognized in bacteriophages, whereby mixed assembly of coat proteins occurs on mixed infection of structurally related viruses. The detection of pseudotypes and phenotypically mixed particles depends on selective assays for genomes and envelopes. As an alternative to neutralization by anti-vesicular stomatitis virus (VSV) serum, pseudotypes may be detected by heat inactivating phenotypically mixed stocks prepared with VSV possessing thermolabile G protein. Very little biochemical work on pseudotypes has been published, owing to the difficulty in obtaining pseudotypes separated from the parental viruses. The full replication of the virus donating antigens to rhabdovirus pseudotypes is not essential, provided that glycoproteins are expressed at the cell surface. Rhabdovirus pseudotypes are frequently more convenient than the parental virus for quantitative neutralization tests.
