New research shows that the unique properties of T cells could make a test that detects virus-specific T cells in a more effective way to assess SARS-CoV-2 exposure before antibodies arise and after they wane.
Using a set of identified “shared” T-cell receptors (TCRs) that are seen across multiple individuals infected with COVID-19, Adaptive Biotechnologies (Seattle, WA, USA) has identified a T-cell signature that can be used for diagnostic purposes. The company is developing a T-cell based diagnostic test that can that detect virus-specific T cells in a more effective way to assess SARS-CoV-2 exposure before antibodies arise and after they wane.
Adaptive recently conducted a head-to-head study in a real-world setting comparing the company’s T-cell test under development with two leading serology tests in 100 patients, ranging from active infection through convalescence. The tests were set at 99.8% specificity to minimize false positives. In the study, 94% of patients were detected as positive by Adaptive’s T-cell test under development vs. 90% (IgG and IgM) and 87% (IgG only) for the serology tests, respectively.
These results, together with a growing body of evidence indicating T cells can be present in the absence of antibodies, suggest the potential utility of Adaptive’s T-cell based approach to detect immune response to SARS-CoV-2 earlier, and in less severe cases, than tests that detect antibody response. Adaptive is currently working with the FDA to generate and package the data required to submit for Emergency Use Authorization (EUA). The company anticipates that the data it continues to generate will expand the clinical applications for its T-cell based testing approach to potentially include assessing pre-existing immunity based on cross-reactive T cells, post infection immunity, and immunity from a vaccine, which may need to be monitored for possible boosters over time.