People who gained immunity either through vaccination or exposure to the original strain of SARS-CoV-2, the virus that causes COVID-19, are likely to have some protection against the pathogens omicron variant. That''s because mutations that led to the variants'' development arent found in the region of the virus that stimulates one type of cellular immune response, according to an international research team from Johns Hopkins Medicine, in collaboration with the National Institute of Allergy and Infectious Diseases (NIA
However, the researchers argue that their findings only relates to a specific cell-mediated immunity the bodys defense against invaders that does not involve circulating antibodies, and that it may be the antibody-related immune response (known as humoral immunity) that fails when omicron causes so-called breakthrough infections.
InmBio, a microbiology journal, was published on March 1, 2022.
According to the study lead author, specific epitopes of a protein that elicits an immune response from the virus are recognized by immune system cells called CD8+ T lymphocytes, or killer T cells. This recognition should therefore be virtually as strong as it should be to the initial form of SARS-CoV-2 in January 2021.
People previously infected with or vaccinated against the original SARS-CoV-2 strain have achieved very similar results, according to other research organizations in the United States and South Africa.
CD8+ T cells are nicknamed killer T cells (they are also known as cytotoxic T cells) because they have the potential to protect foreign invaders such as viruses and bacteria from the body. According to Redd, the convalescent plasma donors have six human leukocyte antigens (cell-surface proteins that regulate the immune system and are part of each individuals genetic profile).
Aaron Tobian, the senior author of the transfusion medicine division, and a pathology professor at the Johns Hopkins University School of Medicine, believes that a large portion of Americans who have been vaccinated against or exposed to the original strain of SARS-CoV-2 might have cytotoxic T cells that can produce an immune response to omicron.
The blood samples used in this study for the research teamsearlier investigation of immune response in convalescent patients were initially collected between 26 and 62 days after the donors remained convalescent. This enabled the donors'' immune response to the virus to be fully maturated and yield CD8+ T cells primed against it. The samples were then stored as a result of the researchers'' determination.
During that assessment, donor samples were sent to ImmunoScape for the task of identifying which T cells had responded to SARS-CoV-2. More specifically, the company''s deep immune cell profiling method showed which virus proteins elicited a T cell-directed response data that might provide valuable insight into the T cells'' functional properties.
The blood samples were examined with 408 different SARS-CoV-2 epitopes from spikes on the virus surface, from the virus capsule, and from nonstructural proteins inside the virus. The researchers found that T cells from the convalescent donors recognized 52 of the 408 epitopes.
According to Redd, researchers examined the 52 epitopes previously identified in convalescent blood samples to see if they had been altered by escape mutations genetic mutations that would enable the virus to avoid being immune to cell-mediated immunity.
According to Redd, there was only one low-prevalence epitope from the omicron spike protein that had a minor change from its predecessor in the original virus. Overall, the omicron variant is known to have some 50-plus mutational differences between it and the original SARS-CoV-2 strain, but it appears the virus has not evolved the capability to avoid T cell recognition.
While significant cell-mediated immunity from the original SARS-CoV-2 through its subsequent versions appears to be maintained, Redd, Tobian, and their partners argue that more research is needed to define why people who have this protection may still get sick from omicron.
