Antibodies that fight the original virus may be vulnerable to Omicron

New studies may explain why so many vaccinated and boosted individuals experienced a breakthrough coronavirus infection caused by the Omicron variant. Researchers at the National Institute of Allergic Infectious Diseases, Johns Hopkins Medicine and the National Institute of Health, have found that fully vaccinated and boost-immunized people have high levels of action against the original strain of SARS-CoV-2. Revealed evidence of producing antibodies. The same little defender does not work well to prevent the Omicron strain from attacking healthy cells.

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“Previous studies have shown that vaccine-induced antibodies respond to the original strain of SARS-CoV-2 by inhibiting the ability of the virus to bind to angiotensin converting enzyme 2. [commonly known as ACE2]Receptors on the cell surface invaded by SARS-CoV-2, “said the lead author of the study. Joel Blankson, Professor of Medicine, Johns Hopkins University School of Medicine. “Our study suggests that these same antibodies reduce ACE2 inhibition by the Omicron strain and open the door to breakthrough COVID-19 infection.”

To conduct their study, Blankson and his colleagues analyzed two types of immune responses to SARS-CoV-2. The cell-mediated immune response is a direct attack on the virus by T lymphocytes or T cells. Researchers have observed these immune responses in 18 healthy, fully vaccinated people aged 23-62 years who experienced breakthrough infections within 14-92 days of receiving the booster COVID-19 vaccine. bottom. Of the participants, 14 received a booster immunization with the Pfizer-BioNTech mRNA vaccine, one received a booster immunization with the Moderna mRNA vaccine, and the remaining 3 received a booster immunization with the Johnson & Johnson viral vector vaccine. ..

Participants with breakthrough infections had a humoral and cell-mediated immune response in 31 people aged 21-60 years who were previously vaccinated with COVID-19 and boosted and were not pre-infected with SARS-CoV-2. It was compared to the immune response of the participants’ controls.

Researchers were unable to document that the breakthrough infection was due to the Omicron strain, but because the Omicron mutant accounted for more than 90% of COVID-19 cases treated at Johns Hopkins Hospital. , They say it can be strong. It was conducted when the study participants became symptomatic.

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“We tested antibody-mediated inhibition of the SARS-CoV-2 spike protein that binds to ACE2 and found that the serum from a breakthrough COVID-19 (probably the result of Omicron infection) was the original antibody. The virus strain was found to contain an antibody that was strongly arrested by Omicron, but did not perform its function when it responded to the Omicron strain, “says Blankson.

According to Blankson, the specific reduction in ACE2-inhibiting antibodies that respond to Omicron differs from that seen in previously studied breakthrough infections with alpha mutants. In these cases, infected individuals were found to have lower overall antibody levels against the original viral strain. The level of antibody that inhibits the binding of peplomer to ACE2 (high in the original strain of virus but decreased in Omicron) was similar in both breakthrough and control participants.

In addition, the level of cell-mediated immunity, as measured by the amount of response T cells recorded, remained strong in both the original and Omicron strains, a breakthrough group and a control group.This was shown in A second recent study examining the plasma of 15 mRNA vaccine recipients, also co-authored by Blankson...

“In both studies, the equivalent strong T-cell response of the original strain and the Omicron strain is such that people like our study participants who have breakthrough COVID-19 cases are usually in the process of illness. I can explain why I experience only mild symptoms, “he explains.