Study Reveals Limitations of Antibodies from Original COVID-19 Strain

Antibody Response to Variants

Research suggests that antibodies generated from the original COVID-19 virus strain are insufficient to combat viral variants. Published in June, the study identified two gene sequences, referred to as “clonotypes,” commonly present in antibodies against the virus responsible for COVID-19. These clonotypes are integral to the antibodies that attach to the spike protein of the virus.

Mechanism of Antibody Protection

The SARS-CoV-2 virus is enveloped in spike proteins that feature a receptor-binding domain (RBD). This specific domain interacts with receptors on human cells, facilitating viral entry and subsequent infection. Antibodies targeting the RBD are crucial as they bind to this domain, obstructing the virus’s ability to infect cells. The clonotypes identified in the study are RBD antibodies that are prevalent among individuals infected with COVID-19.

Implications for Vaccine Design

Dr. Nicholas Wu, a professor of biochemistry and co-author of the study, stated, “Antibody response is quite relevant to everything from understanding natural infection and how we recover from infection to vaccine design. That means we can design vaccines trying to elicit this kind of antibody response, and that is probably going to improve the responsiveness of more individuals to the vaccine.”

Differences in Antibody Effectiveness Against Variants

The study further assessed how the identified clonotypes performed against variants of the virus from South Africa and Brazil. It found that these variants reduced the affinity of the clonotypes for the spike protein. Dr. Wu noted, “Even though this antibody response is very common with the original strain, it doesn’t really interact with variants.” This observation indicates that new variants may reinfect individuals who have previously contracted COVID-19.

Need for Ongoing Research

The differences in immune responses among various strains highlight the potential necessity for vaccine boosters aimed at addressing emerging variants. However, additional research is required to identify the immune responses necessary to protect the broader population from COVID-19 infection.

References

Tan, T.J.C. et al. (2021). Sequence signatures of two public antibody clonotypes that bind SARS-CoV-2 receptor binding domain. Nature Communications; 12:3815. Doi: 10.1038/s41467-021-24123-7.
Touchstone, L. (2021). Antibodies from original strain COVID-19 infection don’t bind to variants, study finds. EurekAlert! Accessed Sept 23, 2021. Retrieved from https://www.eurekalert.org/news-releases/928827.
Image by Gerd Altmann from Pixabay.