Scientists are developing antibody tests to track immunity to SARS-CoV-2 mutants

Experts agree-; the pandemic is not over. Infection is increasing again, fueled by new variants whose immune system is not well prepared.

Researchers in Canada and the United States discovered that antibodies produced in people vaccinated and / or recovered from COVID-19 before 2022 were unable to neutralize the variants circulating today. It is due to the research by.

The study was led by Igor Stagljar, a professor of biochemistry and molecular genetics, at the Donnelly Center for Cellular and Biomolecular Research, at Temerty Faculty of Medicine, and Shawn Owen, an associate professor of pharmaceutics and pharmaceutical chemistry, at the University of Utah ..

journal Nature Communications We have released the results of their survey.

Researchers have developed antibody tests to measure the immunity of study participants, making them a valuable tool for determining who needs boosters and when, saving lives and avoiding future blockages. I hope it will help you.

The truth is still not sure how often our shots should be to prevent infection. To answer these questions, we need a quick and inexpensive quantitative test to specifically measure SARS-CoV-2. Neutralizing antibody, Prevents infection. “

Donnelly Cell and Biomolecule Research Center, Professor of Biochemistry and Molecular Genetics, Igor Stagljar

Many antibody tests have been developed over the last two years. However, only a few of the approved ones are designed to monitor neutralizing antibodies. Neutralizing antibodies coat the viral spike protein to bind to receptors and prevent them from entering cells.

This is an important difference as only a small portion of all SARS-CoV-2 antibodies produced during infection are neutralized. And while most vaccines are specifically designed to produce neutralizing antibodies, it is not clear how much protection they provide against mutants.

“Our method we named Neu-SATiN is as accurate as the gold standard, but faster, cheaper and can be quickly adapted when new variants emerge.” He said.

Neu-SATiN stands for Split Tripert Nanoluciferase-based Neutralization Serological Assay, a new version of SATiN developed last year that monitors a complete IgG pool.

The development of Neu-SATiN was led by Zhong Yao, a senior researcher in Stagljar’s lab, and Sun Jin Kim, a postdoctoral fellow in Owen’s lab, who is the co-lead author of this paper.

The first pinprick test of this type is enhanced by a protein complementation strategy using the fluorescent luciferase protein of deep-sea shrimp. It measures the ability of viral spike proteins to bind to the human ACE2 receptor. Each receptor is bound to a luciferase fragment. The binding brings the luciferase pieces into close proximity, reconstitutes the full-length protein, and emits a glow of light captured by the luminometer device. When the patient’s blood sample is added to the mixture, the neutralizing antibody binds to the spike protein and prevents contact with ACE2. As a result, luciferase remains fragmented and is accompanied by a decrease in the optical signal. The plug-and-play method can adapt to different variants within a few weeks by manipulating variant mutations into pesplomers.

By November 2021, researchers applied Neu-SATiN to blood samples collected from 63 patients with different histories of COVID-19 infection and vaccination. Omicron.

“I thought it was important to monitor the vaccinated people to see if they were still protected and how long they would last,” said a prominent bioengineer at the Donnelly Center. Molly Shoiche, a university professor, and Owen, a postdoctoral fellow, said. “But I also wanted to see if I was vaccinated against one mutant, does it protect you from another?”

Neutralizing antibodies were found to last about 3-4 months when their levels were reduced by about 70%, regardless of infection or vaccination status. Hybrid immunity acquired by both infection and vaccination initially produced higher antibody levels, but these too decreased significantly after 4 months.

Most worrisome, infection and / or vaccination provided good protection against previous variants, but against Omicron, or its subspecies BA.4 and BA.5. Did not provide.

The data showed that both neutralizing antibodies and cell-mediated immunity are a type of immunity provided by memory T cells from infection, vaccination, or both and do not provide protection from Omicron capture. Consistent with data from recent British studies. With a surprising twist, the British group also found that infection with Omicron increased immunity to early strains, but not to Omicron itself. The reason is unknown.

It is important to emphasize that the vaccine still provides significant protection from serious illness and death, Stadljar said. Nonetheless, from his team and other teams, given that the more contagious BA4 and BA5 subvariants can escape the immunity acquired from previous Omicron infections, as evidenced by increased reinfection. The findings added that future vigilance is needed.

“There will definitely be new variants in the near future,” said Stagleger. “Immune monitoring and enhancement of circulating variants is becoming increasingly important, and our methods can play an important role in this because they are fast, accurate, quantitative, and inexpensive.”

His lab is already working with Canadian vaccine maker Medicago to support the decision. Effectiveness of Vaccine candidates for Omicron and its submutants. Meanwhile, U of T is negotiating to license Neu-SATiN to companies that scale up for use in artificial immune surveillance and vaccine development in the pharmaceutical industry.