The researchers determined that most SARS-CoV-2 variants mostly have the same T-cell markets as the original variant, and as a result, the body’s developed immune response along with vaccines would still be able to deal with infections in most cases.
A new study by researchers at the Indian Institute of Technology (IIT) Madras has revealed that spike protein vaccines may offer comprehensive protection against multiple COVID-19 variants that are in circulation right now. The study found that variants like Delta Plus, Gamma, Zeta, Mink and Omicron could be effectively countered using vaccine-induced T-cell responses. Though the research team called for further studies even though they believed that spike-proteins are likely to be effective.
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“The efficacy of vaccines, in this case, different forms of spike protein-based vaccines, depends on whether it can trigger not only the antibody response but also the T-cell response. Efficacy against multiple variants can be assessed by first analysing the epitope sequences of various variants for mutations and if they can effectively trigger T-cells induced in the immunisation process,” explained lead researcher Dr Vani Janakiraman. She works at the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, IIT Madras.
The study examined the possible results if the post-vaccination infections were caused by a variant other than the original strain. Nearly all COVID-19 vaccines being approved for use have been developed on the basis of the original wild strain of SARS-CoV-2. With almost all of the newer strains of COVID-19 having a different molecular structure to the virus’ spike protein, it had been important to determine the efficacy of the vaccines.
The scientists found that the efficacy of a vaccine against a particular strain depends on whether the new strain’s spike protein can trigger the body’s T-cell response. T-cells are a type of lymphocyte or ‘killer cells’ which are important white blood cells of the immune system that are a part of the acquired immune response.
T cells are divided into two groups or epitopes, CD8+ T-cells and CD4+ T-cells. The former is called ‘killer’ T cells as they directly kill viral cells while the latter is called ‘helper’ T cells since they ‘help’ the activity of other immune cells like B-cells, which are responsible for creating antibodies.
The researchers were able to determine that most SARS-CoV-2 variants mostly have the same T-cell markets as the original variant. As a result, the body’s developed immune response along with vaccines would still be able to deal with infections in most cases despite these newer variants having developed mutations to evade the body’s antibody immune response.
“We found that at least 90 percent of both CD4+ and C D8+ epitopes were conserved in all the variants except Omicron, but even in Omicron, nearly 75 percent and 80 percent of CD4+ and CD8+ epitopes were conserved,” Dr Janakiraman said.
“This means that the changes to the epitopes are not so large enough to evade the T-cell immune response that the body learned through vaccination,” she added.
(Edited by : Sudarsanan Mani)