Long-term persistence of RBD+ memory B cells encoding neutralizing antibodies in SARS-CoV-2 infection

Considerable concerns relating to the duration of protective immunity against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) exist, with evidence of antibody titers declining rapidly after infection and reports of reinfection. Here, we monitor the antibody responses against SARS-CoV-2 receptor-binding domain (RBD) for up to 6 months after infection. While antibody titers are maintained, ∼13% of the cohort’s neutralizing responses return to background. However, encouragingly, in a selected subset of 13 participants, 12 have detectable RBD-specific memory B cells and these generally are increasing out to 6 months. Furthermore, we are able to generate monoclonal antibodies with SARS-CoV-2 neutralizing capacity from these memory B cells. Overall, our study suggests that the loss of neutralizing antibodies in plasma may be countered by the maintenance of neutralizing capacity in the memory B cell repertoire. [Display omitted] Decay of antibody binding to RBD and spike antigen after 6 months11 of 81 (13.6%) participants revert to background neutralizing levelsDespite declining antibody titers, robust memory B cell populations are observedMemory B cells retain potent neutralizing capacity Abayasingam et al. report that despite the declining anti-RBD antibody titers and neutralizing capacity of antibodies in the serum at 6 months, the memory B cells still contain RBD-specific reactivity that have the capacity to generate antibodies that can neutralize SARS-CoV-2 in vitro.