Researchers at IIT Madras have shown that spike protein vaccines may be effective against multiple variants of the Coronavirus (SARS COV-2).

The results of the study suggest that the attack by Delta plus, Gamma, Zeta, Mink and Omicron may be dealt with by vaccine-induced T-cell responses despite the compromised neutralising antibodies responses. While further experimental verification is called for, the researchers believe that the present spike protein vaccinations are likely to be efficacious against circulating variants of Coronavirus, says a release from the institute.

The researchers set out to find out what would be the response if the post-vaccination infections were caused by a variant other than the original Wuhan strain incorporated in vaccine preparations. In variants of SARS COV-2, there are molecular level changes to the spike protein of the virus, and these variations may include the regions of protein sequences that are recognised by T-cells called epitopes.

Understanding the effect of these variations on the immune response can give some clarity about the efficacy of vaccination against the variants of SARS COV- 2.

Finding of the research

The research was led by Vani Janakiraman, Assistant Professor, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, IIT Madras. The efficacy of different forms of spike protein based vaccines depends on whether it can trigger the antibody response and 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, said Janakiraman

The vaccines could be considered effective against the variants if there are less mutated epitopes in their spike proteins and, if the mutated epitopes can still induce an immune response comparable to that elicited by original/native epitopes. Vaccination is a process in which a milder form of the virus or a part of the virus is introduced into the body. Pieces of a protein called epitopes of the injected virus/viral part trigger an immune response in the body.

In the case of spike protein mRNA vaccination, a strand of messenger-RNA is introduced into the host, which teaches the cells to make the protein, which, in turn, is chopped up into epitopes and presented to T-cells. This ultimately triggers the body’s immune response. In both cases, the response is remembered by the body to guard against future infections.

The IIT Madras team sought to investigate how many of the epitopes in the variants are mutated and whether the mutated epitopes can alter the immune response to vaccination in order to assess vaccine efficacy, the release said.