The value of measuring T cell response in COVID-19
The value of measuring T cell response in COVID-19

The value of measuring T cell response in COVID-19

While public health officials and clinicians struggle with the ever-changing COVID-19 strains and the limiting efficacy of vaccines, it is a common discussion to avoid immunity as the emphasis has shifted from complete protection of humans against SARS-CoV-2 to reducing virus severity including hospitalization. and mortality.

Vaccines and boosters may be effective for a few months, but declining immunity has led to more widespread breakthrough infections. And vaccine efficacy studies continue to look at neutralizing antibodies as the key measure of protection and have shown limited interest in measuring T cell response to evaluate long-term protection.

Much of the focus in vaccine development and immunity monitoring has been on the role of neutralizing antibodies (nAbs), with less emphasis on understanding the role of T cells, memory B cells and non-neutralizing antibodies that can provide protection via mechanisms such as. opsonization and antibody-dependent cellular cytotoxicity, “investigators wrote in a paper written in Immunology of Science.

“The neutralizing antibodies we’re looking for only bind to a very small portion at the tip of the tip protein,” said Harlan Robins, PhD, co-founder and CSO, Adaptive Biotechnologies. “But the T cell response is spread throughout the genome.”

The role that T cells have played in understanding COVID-19 immunity and vaccine response has been limited at best. Measurement of T cell response could help provide a more complete picture of protection after vaccination. A growing body of evidence indicates that T cells may be an important correlate for protection and should be considered as an endpoint for clinical vaccine trials and the development of next-generation vaccines and boosters..

Seattle-based Adaptive Biotechnologies is a company focused on the adaptive immune system for diagnosing and treating disease. By looking at T cells and COVID-19, the company has developed their T-Detect test to determine a recent or past COVID-19 infection. This test has received a Food and Drug Administration Emergency Use Authorization.

Adaptive has another test, immunoSEQ T-MAP COVID, which allows researchers to determine previous SARS-CoV-2-specific immune response in research samples and track longitudinal responses.

Part of the problem has been the difficulty of T cell measurement. While B cells are easily detected, Robins explains, T cell measurement has been challenging. “T cells do not secrete anything – which means you have to look at the cells themselves – and to understand their functional properties, you have to keep them alive,” Robins said. “… We tried to map the primary functional property, which is what they bind to … this information is contained in the DNA of the T cells, which are super stable. So if we could read that piece of DNA directly to determine the function of the cell, we no longer needed living cells to make this assessment. “

Along with testing, Adaptive has partnered with vaccine manufacturers to consider T-cell-focused COVID-19 vaccines. “Imagine if you could do a much better job and deliberately create a vaccine where it is focused on the T cell response,” Robin explained. “You want to supplement it with an approach that also generates neutralizing antibodies, but a broad T-cell response can provide a base that should protect you for a significant period of time from becoming seriously ill.”

Infection talked to Robins about how technology and chemistry go together to create more medical data in this area, and whether regulators should also look at T-cell evaluation along with antibody evaluation in COVID-19 vaccine trials.

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