Impact of SARS-CoV-2 variants on antibody tests

Since end of 2020, different SARS-CoV-2 variants have appeared worldwide − alpha (B.1.1.7), beta (B.1.351), gamma (P.1/B.1.1.128) and delta (B1.617.2) − which are in part more contagious than the original virus type and are therefore spreading more quickly within populations.

These variants reveal genetic changes (mutations) in the so-called receptor binding domain (RBD), which is critical for the virus to enter into human host cells. Also, the RBD is an important component of the antigen which is applied in most of our antibody test systems, i.e. the S1 domain of the SARS-CoV-2 spike protein. Despite these mutations, effects on the performances of the antibody tests have not been expected because single mutations of an antigen usually have no impact on the binding characteristics of the corresponding antibody.

This was now also experimentally confirmed by an internal study using samples from patients who had been infected with SARS-CoV-2 variants. In total 27 samples from patients infected with the alpha, beta or gamma variant of SARS-CoV-2 were analysed with our S1-based test systems Anti-SARS-CoV-2 ELISA (IgA) and Anti-SARS-CoV-2 QuantiVac ELISA (IgG).

The results show that antibodies against the SARS-CoV-2 variants alpha, beta and gamma can also be reliably detected with our S1-based test systems. Considering a combined determination of specific IgA and IgG antibodies, a hit rate of 100% was reached.

More information on our test systems for COVID-19 diagnostics can be found here:

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