A human coronavirus evolves antigenically to escape antibody immunity

Author summary Hopes for controlling SARS-CoV-2 rely on vaccination or infection to confer immunity that protects against subsequent infection. However, the common-cold seasonal coronaviruses re-infect people every few years. It has been unclear if these re-infections occur because immunity wanes rapidly, or because the virus evolves to escape immunity elicited by prior infection. Here we investigate the second hypothesis in the context of the common-cold coronavirus 229E. We test how well antibodies in old human sera neutralize both contemporaneous old 229E viruses, and more recent viruses that evolved after the sera was collected. We find that as 229E evolves, its spike protein accumulates mutations that escape neutralization by older human sera. The rate at which viral evolution degrades immunity varies among individuals, but in some cases less than a decade of evolution is sufficient to completely eliminate neutralization by human sera that is potent against contemporaneous viruses. Many of the viral mutations occur in the same regions of the spike (the RBD and NTD) that are changing in emerging variants of SARS-CoV-2. Therefore, our results suggest that coronavirus vaccines may need to be periodically updated to keep pace with viral evolution. There is intense interest in antibody immunity to coronaviruses. However, it is unknown if coronaviruses evolve to escape such immunity, and if so, how rapidly. Here we address this question by characterizing the historical evolution of human coronavirus 229E. We identify human sera from the 1980s and 1990s that have neutralizing titers against contemporaneous 229E that are comparable to the anti-SARS-CoV-2 titers induced by SARS-CoV-2 infection or vaccination. We test these sera against 229E strains isolated after sera collection, and find that neutralizing titers are lower against these future viruses. In some cases, sera that neutralize contemporaneous 229E viral strains with titers >1:100 do not detectably neutralize strains isolated 8-17 years later. The decreased neutralization of future viruses is due to antigenic evolution of the viral spike, especially in the receptor-binding domain. If these results extrapolate to other coronaviruses, then it may be advisable to periodically update SARS-CoV-2 vaccines.

Automated summary

This study investigates the evolution of human coronavirus 229E and finds that as the virus evolves, mutations in the spike protein can escape neutralization by antibodies in old human sera. The results suggest that viral evolution may impact immunity, highlighting the need for periodic updates to coronavirus vaccines.