With the COVID-19 pandemic in its nineteenth month, questions surrounding immunity against the SARS-CoV-2 coronavirus are rampant. With aggressive vaccination drives across the world, and infected individuals recovering from the disease, it is important to ascertain whether these individuals possess antibodies associated with protection against the virus. Therefore, rapid, reliable, and inexpensive tests are paramount in this pursuit. Providing such a testing option, scientists have developed a rapid antibody test that provides results in just eight minutes.
A new interdisciplinary study by researchers from the Technical University of Munich (TUM) has described a new automated microarray rapid test called 'CoVRapid' that is highly specific and highly sensitive in identifying the three most crucial antibodies associated with immunity. The study was published in the journal Analytical and Bioanalytical Chemistry.
"The present research begs questions like: How well do vaccinations work? How long does immunity last? When will vaccinations need to be readministered? With its high sensitivity, our CoVRapid will help us find the answers to these questions," said Julia Klüpfel, lead author of the study, in a statement.
Scoring Over Other Tests
As of now, there are over 20 testing procedures that can help in finding whether an individual has developed antibodies against the SARS-CoV-2 virus. However, the waiting time for these tests is varied—ten minutes to two-and-a-half hours. The sensitivity of the several methods is also reduced by matrix effects (influences on an analytical method by all other components of the sample except the particular compound being quantified).
Also, numerous steps are involved in higher sensitivity essays which lead to increased costs. Importantly, most tests are capable of identifying only one kind of antibody, thereby, compelling to make a choice between testing for immunity via vaccination, or through infection.
However, 'CoVRapid' scores over other tests in the mentioned areas. The test is an automated, flow-based chemiluminescence microarray immunoassay (CL-MIA). It enables the detection of IgG (Immunoglobulin G) antibodies towards the coronavirus' RBD (receptor-binding domain), S1 fragment (spike protein), and N protein (nucleocapsid protein) in humans plasma and serum.
Quick, Extensive, and Accurate
CoVRapid's design is rather simple. The measurement of the antibodies is executed on a foil-based sensor chip utilizing an MCR microarray analysis platform produced by GWK Präzisionstechnik GmbH, a Munich-based manufacturer of automated laboratory equipment. A few minutes—eight minutes currently—after the introduction of the blood sample, the device displays the results.
During the test, IgG antibodies against a protein fragment of the novel coronavirus' RBD, S1 fragment, and the N protein are examined simultaneously. Though the procedure still requires eight minutes, the authors state that the waiting time can be slashed to four minutes using data from the current research. The automated microarray technology can accommodate around 100 measurement points on a single chip.
The 'CoVRapid' test was assessed using a set of 65 SARS-CoV-2 serology negative or positive samples. This resulted in 100 percent diagnostic sensitivity and 100 percent diagnostic specificity; thereby outperforming other commercial tests carried out using the same sample set.
Potential for Integrating Newer Variants
The blueprint of 'CoVRapid' provides for easy integration of proteins from new mutant strains within the chip. For this next phase, the team is collaborating with ISAR Bioscience, a producer of viral proteins (who also modify them for analytical purposes). Moreover, the mechanism employed for the fixing of the proteins on to the sensor chip is one that has been tested and evaluated for several years now.
"We have already developed reliable rapid tests for antibiotics in milk and for Legionella using this technology platform. The system has already proven itself in practical use. Our 'CoVRapid' rapid test may thus be deployed in clinics, medical offices and research laboratories in the very near future," explained Dr. Michael Seidel, corresponding author of the study.
Nevertheless, 'CoVRapid' can do more than just detecting antibodies. The sensitivity of the test is so high that the concentration of the antibodies within a sample can also be calculated. As a long-term goal of the research, the authors intend to include other equally potent pathogens in the panel in order to apply the assay for uses such as the evaluation of the effectiveness of influenza vaccines, among others.
