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An antigenic microchip has been created to identify COVID-19 patients
Anastasia Gorshkova, PCR.news
A preprint has appeared in the bioRxiv database (de Assis et al., Analysis of SARS-CoV-2 Antibodies in COVID-19 Convalescent Plasma using a Coronavirus Antigen Microarray), in which scientists from the USA talk about the effectiveness of the microchip they developed for detecting antibodies to various coronaviruses, including SARS-CoV-2, SARS-CoV and MERS-CoV. The specificity of the test was evaluated on the plasma of people who had been ill with COVID-19 and plasma obtained before the outbreak of the pandemic.
Currently, in most countries, PCR-based tests are used to diagnose coronavirus infection in people with symptoms of the disease and in people at risk. This approach underestimates the number of people who have been ill. In addition, the sensitivity of the tests is only 60-80%, and their effectiveness depends on the correctness of the sampling and the titer of the virus in the patient.
In order to reliably estimate the percentage of infected people, it is necessary to conduct serological tests to determine antibodies to the pathogen, but the optimal combination of viral antigens for accurate analysis is still unknown.
Scientists from the USA and Switzerland have developed a microchip containing 67 antigens of SARS-CoV-2 and other known coronaviruses, each in four repetitions. The antigen panel includes nucleocapsid (NP) proteins and S-proteins both in the form of separate S1 and S2 domains, and in the form of a complete protein. Two types of plasma were used to test the microchip: convalescent plasma from patients diagnosed with COVID-19, confirmed by a PCR test, as a positive control, and plasma obtained before the outbreak of the epidemic as negative.
The microchip has demonstrated its effectiveness for detecting antibodies specific specifically to SARS-CoV-2. Cross-reactivity of antibodies to nucleocapsid proteins was observed only between SARS-CoV-2 and SARS-CoV, but not MERS-CoV or seasonal coronaviruses, despite the high homology of NP proteins in beta-coronaviruses. In addition, it turned out that the quantitative difference between the binding of antibodies to the S2 domain of SARS-CoV-2 in the positive and negative control groups is large enough, which makes it possible to effectively distinguish the plasma of ill and uninfected people.
The microchip can be useful both for diagnostics and for epidemiological studies. High-performance and reliable detection of specific antibodies to SARS-CoV-2 is important for accurate assessment of the true prevalence of the disease.
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