Skip Ribbon Commands
Skip to main content


​​​​SARS-CoV-2​ Immunoassays

​​​​​​Nexelis GH-VAP Services​

Nexelis has developed and qualified GCLP assays to assess human and non-human primates (NHP) immune responses to SARS-CoV-2 vaccine candidates and biologics. Nexelis provides these standardized assays via the GH-VAP program to support development efforts funded by the Bill and Melinda Gates Foundation, CEPI and their partners. These efforts will generate the immunological data required by these partners in the industry-grade high quality lab environment required for regulatory purposes. Assays will be validated as needed.

Binding assays available via GH-VAP include ELISA against the solubilized pre-fusion stabilized spike protein, the receptor binding domain (RBD) of the S1 subunit, and the nucleocapsid protein of the SARS-CoV-2 virus. The Nexelis Protein Sciences team will express in HEK293 cells, purify and characterize these antigens to ensure suitability for assay use and consistency between lots. The Nexelis Protein Sciences team will make these materials available as requested by the Foundation for assay comparability and bridging purposes.

Nexelis also provides a qualified pseudovirus neutralization assay (PNA) using a VSV delta G backbone containing the spike protein sequence from the Wuhan 1 isolate of SARS-CoV-2 with a deletion of the cytoplasmic tail. Additional constructs, such as the D614G polymorphism, are under evaluation. Through a strategic partnership with Public Health England (PHE), a panel of samples has been analyzed in both the PNA and wild-type neutralization assay to ensure the PNA’s use as a surrogate. The Nexelis team will also facilitate through subcontracting wild-type neutralization assays if required.

In addition to the clinical assays above, the Nexelis team has standardized/qualified assays for key non-clinical target species, i.e. ferret, hamster, mouse, and NHP. These assays are used for pre-clinical research and serve as a template for subsequent qualified assays for human trials. Further, development and qualification of IFN-gamma ELISpot and quantitative PCR for virus detection are underway and will be available via GH-VAP.

Nexelis will be validating the assays in the coming months to support Phase IIb/III studies. The current qualified methods have been deployed to support Phase I/IIa studies. In addition to partnering with PHE for the comparison of the PNA and wild-type neutralization assay, Nexelis is participating in collaboration efforts to ensure assay/reagent comparability, e.g. SNACS and NIBSC efforts.

​About Nexelis​


With unrivaled expertise in immunology on both sides of the client/CRO relationship, and operating sites in North America (East and West Coast) and Europe, Nexelis is a leading provider of assay development and advanced laboratory testing services in the infectious diseases, metabolic diseases, and oncology fields. Our versatile team of scientists, working with our advanced technology platforms, were instrumental in the development, qualification, validation, and large-scale sample testing of assays that supported the FDA filing of almost 100 new molecular entities, including blockbuster vaccines, anti-viral drugs, and immunotherapy, gene and cell therapy products. For more information, please visit: www.nexe​

​ ​


© 2021 Bill & Melinda Gates Foundation. All Rights Reserved.

Privacy & Cookies Notice​ | Terms Of Use  |  Be Aware of Fraudulent Activity      ​