Attana and Linnaeus University have published the first part of the science behind immunity profiles

In the publication Quartz Crystal Microbalance Platform for SARS-CoV-2 Immuno-Diagnostics, Attana's QCM technology has been evaluated for reproducibility, sensitivity, linearity, and specificity for detection of SARS-CoV-2 antibody binding. The results have been compared with ECLIA and CLIA. A total of 119 human serum samples were compared, of which 59 were positive with ECLIA, 52 with CLIA and 48 with QCM. In conclusion, the QCM-based SARS-CoV-2 IgG immunoassay showed high reproducibility and linearity, as well as good coherence with the reference methods.

Factors that affect the results are partly experiment-dependent and partly interaction-dependent. Experiment dependence is, for example, that the different techniques used different types of antigens, QCM S-antigen, ECLIA N-antigen and CLIA S- and N-antigen and different incubation times. QCM measures in real time for two minutes (but has no direct incubation time), ECLIA has nine minutes incubation time and CLIA has a two-step incubation totaling 45 minutes including rinse step.

Interaction dependence is linked to biological properties such as the kinetics of the antibody-antigen interaction and the antibody titer. A low titer and fast association and dissociation rate will initially give higher signal than a low titer with slow kinetics. One of the advantages of real-time measurement in QCM is precisely that the kinetics are determined and thereby can provide additional diagnostic information, i.e. about the neutralizing capacity of the antibodies. Since the purpose of this article was to validate Attana's QCM technique against existing techniques, the kinetics are not included in the results, but they will be in a further publication.

In summary, this has laid the foundation for the current joint project led by Prof. Ian Nicholls at Linnaeus University which aims to develop immunity profiles for more pathogens.

Related Publications:

https://www.nature.com/articles/s41467-020-20251-8

https://europepmc.org/article/med/29399414

https://www.nature.com/articles/s41467-023-42408-x

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10457302/

https://www.frontiersin.org/articles/10.3389/fvets.2023.1243853/full