What is a pseudovirus? A pseudovirus is a recombinant viral particle artificially created by pseudotyping, and its core and envelope proteins are derived from different viruses. The parent virus used to generate a pseudovirus is typically a rhabdovirus (e.g., vesicular stomatitis virus (VSV)) or a retrovirus (e.g., murine leukemia virus (MLV) or human immunodeficiency virus 1 (HIV-1)). Pseudoviruses are considered useful virological tools because of their safety and versatility, especially for emerging and re-emerging viruses. One of the advantages of employing pseudoviruses is that they can mimic the infectious process of the novel virus and removes the dangerous viral components. Therefore, pseudoviruses are widely used in the research of cellular tropism, receptor recognition, virus inhibition, as well as the development and evaluation of antibodies and vaccines.

It has now been more than a year since the start of the COVID-19 pandemic, which has claimed millions of lives and dramatically changed people's normal lifestyles. COVID-19 vaccination is a critical prevention measure to help end the COVID-19 pandemic. However, the success of COVID-19 vaccines is inseparable from the contribution of pseudoviruses. In particular, a pseudovirus-based neutralization assay based on a VSV pseudovirus production system was developed for evaluating neutralizing antibodies against SARS-CoV-2 during the development of the vaccine. Given the difficulties and safety issues associated with using live viruses, pseudovirus-based assays are essential for researchers to understand how viruses infect cells and how therapeutics and vaccines can be developed to stop them.

The neutralizing antibody test based on the pseudovirus system simulates the biological process of the neutralizing antibody blocking the virus from entering the cell, which can directly reflect the protective effect of antibodies. Compared with traditional methods, this approach has the advantages of simple, rapid, accurate, reliable, high throughput, and high sensitivity.

In addition, pseudoviruses cannot replicate sequentially and have the ability of only a single-round infection, thus eliminating the hidden danger of biosafety caused by highly pathogenic and highly infectious viruses. Because of these incredible benefits, pseudoviruses play an important role in the study of viral pathogenesis, ADCC assay, drug screening, etc.

※ Mechanistic study of viral infection
Pseudoviruses have not only been widely used for in vitro studies of the interaction between viral pathogens and host cells, but also proved to be very useful for in vivo studies, especially in the mechanism of virus infection and biological distribution.

※ Application of antibody-dependent cell-mediated cytotoxicity assay
Recently, researchers have developed pseudovirus systems for the analysis of antibody-dependent cell-mediated cytotoxicity (ADCC) activity, which may be a better choice than using target cells transfected with DNA plasmids. The reason for using pseudoviruses in ADCC assays is that the surface proteins of pseudoviruses largely retain their natural conformation, and parts of these proteins still remain on the surface of target cells after infection.

※ Drug screening
A variety of studies have been conducted by using pseudoviruses to screen small‐molecule compounds including those against LASV, EBOV, MARV, SARS‐CoV, HIV-1, and influenza H5N1. In the process of drug screening, the pseudovirus system can be used to quickly and accurately measure the effective concentration of drugs. More importantly, it can also be used to determine the exact stage at which an antiviral drug acts during viral replication.


Author's Bio: 

A big fan of biological science and technology