Neutralizing Antibody (NAb) assays
The antibody response is crucial for preventing viral infections and can also contribute to the resolution of infections. When a body is infected with a virus, antibodies are produced against epitopes to multiple virus proteins. A subset of these antibodies can block virus infection by a process that is called neutralization. While standard immunoassays (e.g., ELISA) can be used to detect anti-virus-specific antibodies including neutralizing antibodies (NAbs), they cannot distinguish NAbs functions from the other antigen specific antibodies measured, that are participating in the immune response. NAb assays provide this functional readout.
Other applications for usage of NAb measurements include evaluation of adverse immune responses by the generation of e.g., neutralizing antibodies, which can bind to the biotherapeutic drug product administered and prevent it from performing its intended biologic function, in turn negatively impacting the product’s efficacy and safety profile.
Independently of the intended objectives of the NAb assay, we can customize such assays for our clients in our BSL2 laboratory. We at CTL are using microneutralization assays using relevant cell lines and pseudoviruses. The selected pseudovirus is able to bind to the cell and mediate cell fusion resulting in the cells “infection” by the pseudovirus, that will induce in the cell production of e.g., green fluorescent protein (GFP). We are performing the single cell enumeration by using e.g., the GFP expressing cell read out. The provided test serum or plasma, if it contains NAb, will inhibit and neutralize the infection of the cells with the pseudovirus and subsequently reducing the number of cells that will be e.g., GFP expressing. The fluorescent cells (GFP positive) will be counted and the percent neutralization calculated. This biological process is in close relation to the function of the NAb in the body and thus closely reflects the in vivo processes.
We have established and validated diverse NAb assays for our clients and have for example an actively ongoing functional readout that allows to detect NAbs specific to the SARS-CoV-2.
- Client specific NAb Assays
- Anti-SARS-CoV-2 NAb Assay