The Coronavirus SARS-CoV-2 causing COVID -19 has infected in excess of 12 million people around the world and killed more than 500,000. It has also caused widespread socioeconomic disruption and damage. Various companies and institutes are racing to develop an effective vaccine on priority. A host of these vaccines are in the clinical trial stage and Russia has announced completion the trial. However, the scientists still don’t have a full understanding of the molecular features that would define a protective antibody response to the disease.
A new study has enabled us to take a step closer to understanding the antibody. A team led by scientists at Scripps Research have announced the discovery of a common molecular feature found in many of the human antibodies that neutralize SARS CoV2.
Using X-ray crystallography, the team imaged two antibodies attached to their target site on SARS-CoV-2 and the resulting atomic-structure details of this interaction might potentially help the vaccine designers.
These antibodies are Y-shaped proteins made in immune cells called B-cells. Each B-cell makes a specific antibody type, or clone, which is encoded by a unique combination of antibody genes in the cell. The scientists found that an antibody gene called IGHV3-53 was the most common of the genes among the blood samples collected over past few months. These antibodies mutated only minimally from the original versions and hence it is easier to induce this same process with a vaccine. The generation of new B-Cells was not required to contain the virus.
Another set of IGHV3-53 antibodies were imaged to find the binding capacity to their target on SARS-CoV-2. The target, known as the receptor binding site, is a crucial structure on the viral “spike” protein that normally connects to a receptor on human cells to begin the process of cell infection. Many of the antibodies that neutralize SARS-CoV-2 appear to do so by blocking this virus-receptor connection.
The researchers say that the identification of IGHV3-53-encoded antibodies as key elements of the immune response to COVID-19 suggests that levels of these antibodies might be useful as an indirect marker of success in ongoing and future vaccine trials.