Pseudovirus Neutralization Assay Service for SARS-CoV-2

What are viral pseudotyped particles?
“Viral pseudotyped particles (PP) are enveloped virus particles that harbor heterologous envelope glycoproteins on their surface and a genome lacking essential gene. ...They have proven to be very useful tools used in research with many applications, such as enabling the study of entry pathways of enveloped viruses … ” [Jean Kaoru Millet, etc. Bio Protoc. 2016 Dec 5;6(23): e2035]

In general, MLV or MuLV (murine leukemia virus) -based virus system is a better choice than HIV-based lentivirus system for making pseudoviral particles in regards of lab safety and product quality. We have generated replication-deficient MLV-based Coronavirus Spike-pseudotyped particles (Spike-PP) for critically important SARS-CoV-2 variants. For each variant, the Spike-PP are bi-layer lipid membrane particles with the spike protein trimers on the outer surface and Gag-Pol from MLV as the inner backbone, enclosing the firefly luciferase mRNA. There are estimated on average ~10 spike trimers on the surface of the Spike-PP of the original SARS-CoV-2 strain. 

Using our replication-deficient MLV (or MuLV, murine leukemia virus) virus systems and stable cell lines (i.e. HEK293-ACE2, HEK293-ACE2-TMPRSS2, vero, CHO, etc.), we could
1) constuct the pseudoviral particles pseudotyped with specified membrane protein, wildtype or with specific mutation(s);
2) study the interactions between the memberane protein (i.e. the spike protein) and the host cell receptor(s) in specific conditions;
3) validate the candidates that blocks the interaction between the membrane protein and the host cell receptor;
4) screen convalescent serum samples or monoclonal antibodies for neutralizing antibodies;
5) screen molecules for those blocking the interaction between Spike and the host cell receptor(s).
and more...

We provide the above services routinely, and have served customers from pharmaceutical and biotech industry, hospital and life science institutes. Through the collaboration with the frontline academic laboratories, we have learned that the results obtained from the neutralization validation using our SARS-CoV-2 pseudoviral particles aligned with those of the neutralization validation using live SARS-CoV-2 virus. 

Please click here for a more detailed description on our constructed pseudoviral particles, neutralization assays, and the examples.

            An example:   Dose-response curves of serum or purified antibody samples for determining their IC50s. 

For constructing pseudoviral particles and the related services for other viruses, please inquire:

Browse for some of our existing pseudovirus-related products:  Pseudovirus & Stable Cell Line 

Browse for our recombinant protein and antibody products, i.e. neutralization antibodies, recombinant spike proteins for variants: Coronavirus Research Tools  

Selected Citation of our SARS-CoV-2 pseudoviral particles applied in COVID research:

1) A novel linker-immunodominant site (LIS) vaccine targeting the SARS-CoV-2 spike protein protects against severe COVID-19 in Syrian hamsters. Emerging Microbes & Infections, May 2021.

2) Immunogenicity and Neutralizing Activity Comparison of SARS-CoV-2 Spike Full-Length and Subunit Domain Proteins in Young Adult and Old-Aged Mice. Vaccines, Feb. 2021.

3) Serum Antibody Profile of a Patient With Coronavirus Disease 2019 Reinfection. Clinical Infectious Diseases, Sept. 2020.

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