Pseudotyping is the process of producing viruses or viral vectors in combination with foreign viral envelope proteins. The result is a pseudotyped virus particle, also called a pseudovirus.[1] With this method, the foreign viral envelope proteins can be used to alter host tropism or increase or decrease the stability of the virus particles. Pseudotyped particles do not carry the genetic material to produce additional viral envelope proteins, so the phenotypic changes cannot be passed on to progeny viral particles. In some cases, the inability to produce viral envelope proteins renders the pseudovirus replication incompetent. In this way, the properties of dangerous viruses can be studied in a lower risk setting.[2]
Pseudotyping allows one to control the expression of envelope proteins. A frequently used protein is the glycoprotein G (VSV-G) from the Vesicular stomatitis virus (VSV) which mediates entry via the LDL receptor. Envelope proteins incorporated into the pseudovirus allow the virus to readily enter different cell types with the corresponding host receptor.