While fully vaccinated and grown ones produce higher levels of antibodies that work against the original strain of SARS-CoV-2, the same little protectors don’t do as well to stop the Omicron strain from attacking healthy cells. , found researchers from Johns Hopkins universities in the US.
“Previous research has shown that vaccine-induced antibodies react to the original strain of SARS-CoV-2, inhibiting the virus’s ability to bind to angiotensin-converting enzyme 2. [commonly known as ACE2]A receptor on the surface of a cell through which SARS-CoV-2 enters,” said Joel Blankenson, professor of medicine at the university’s School of Medicine.
“Our study shows that the same antibodies produce less ACE2 inhibition with the Omicron strain, opening the door to a successful COVID-19 infection,” he said.
For the study, published in the Journal of Clinical Investigation Insight, Blankson and team analyzed both humoral (SARS-CoV-2 specific antibodies circulating in the bloodstream and produced by B lymphocytes, or B cells) and cellular (direct attack on the virus). . T lymphocytes, or T cells) immune response in 18 healthy and fully vaccinated people who experienced successful infection within 14 to 92 days after receiving a COVID vaccine booster.
The humoral and cellular immune responses of those participants with successful infection were compared to a control group of 31 participants aged 21 to 60 years, who also received a COVID vaccination and booster, and had no prior infection with SARS-CoV-2. was not.
“When we tested antibody-mediated inhibition of SARS-CoV-2 spike protein binding to ACE2, we found that the serum of study participants with breakthrough COVID-19 – most likely the result of omicron infection – had antibodies. which originally strongly inhibited binding to the strain virus as expected, but did not perform that function as well when responding to the Omicron strain,” Blankenson said.
Levels of antibodies that inhibit spike protein binding to ACE2 — high for the original strain virus but low for Omicron — were similar for both participants in the breakthrough infection and control group.
“Comparable strong T cell responses to the original and Omicron strains may explain why people who have had COVID-19 cases typically experience only mild symptoms during the course of their illness,” Blankenson explained.