SARS-CoV-2 monoclonal antibody treatment followed by vaccination shifts human memory B cell epitope recognition suggesting antibody feedback

Abstract

Therapeutic anti-SARS-CoV-2 monoclonal antibodies (mAbs) have been extensively studied in humans, but the impact on immune memory of mAb treatment during an ongoing immune response has remained unclear. Here, we evaluated the effect of infusion of the anti-SARS-CoV-2 spike receptor binding domain (RBD) mAb bamlanivimab on memory B cells (MBCs) in SARS-CoV-2-infected individuals. Bamlanivimab treatment skewed the repertoire of memory B cells targeting Spike towards non-RBD epitopes. Furthermore, the relative affinity of RBD memory B cells was weaker in mAb-treated individuals compared to placebo-treated individuals over time. Subsequently, after mRNA COVID-19 vaccination, memory B cell differences persisted and mapped to a specific defect in recognition of the class II RBD site, the same RBD epitope recognized by bamlanivimab. These findings indicate a substantial role of antibody feedback in regulating human memory B cell responses, both to infection and vaccination. These data indicate that mAb administration can promote alterations in the epitopes recognized by the B cell repertoire, and the single administration of mAb can continue to determine the fate of B cells in response to additional antigen exposures months later.

Keywords: Bamlanivimab; Biological Sciences (Immunology); COVID-19; SARS-CoV-2; mAb therapy; memory B cells.

Figure 1.. Effect of bamlanivimab after 28 days of treatment in COVID-19 cases

(A) SARS-CoV-2 infected people were treated with 700 mg intravenous dose of bamlanivimab (B-C) Spike S1 (B) and RBD (C) IgG titers in the placebo and mAb-treated groups (D) Representative gating strategy for spike-binding memory B cells (“MBCs”) in SARS-CoV-2 infected (top image) and uninfected humans (bottom image) (Refer also to Fig. S5). (E) Representative gating strategy for RBD-binding MBCs in SARS-CoV-2 infected (top image) and uninfected humans (bottom image). (F-G) Frequency of Spike (F) and RBD (G) MBCs among total memory B cells (IgD, CD27 ) (H) Frequency of RBD MBCs within the Spike MBCs population (I) Frequency of non-RBD MBCs within the Spike MBCs population (J) Affinity of RBD MBCs determined by the ratio MFI from the RBD probe (PE-CY7)/ MFI from immunoglobulin-associated beta (CD79b) (K-M) Frequency of RBD MBCs expressing IgG (K), IgM (L) or IgA (M). Means are shown. An unpaired, non-parametric Mann-Whitney test was used to compare the different groups. p-values are shown in the graphs and considered significant if lower than 0.05. Sample size: treatment group n= 25 and placebo group n=21

Figure 2.. Effect of bamlanivimab after 24 weeks of treatment in COVID-19 infected adults

(A-B) Frequency of Spike (A) and RBD (B) MBCs among total memory B cells (IgD, CD27 ) (C) Frequency of RBD MBCs within the Spike MBCs population (D) Frequency of non-RBD MBCs within the Spike MBCs population (E) Affinity of RBD MBCs determined by the ratio MFI from the probe PE-CY7 divided by the MFI from immunoglobulin-associated beta (CD79b). (F-H) Frequency of RBD MBCs expressing IgG (F), IgM (G) or IgA (H) Means are plotted in the graphs. An unpaired, non-parametric Mann-Whitney test was used to compare the different groups. p-values are shown in the graphs and considered significant if lower than 0.05. Sample size: treatment group n= 18 and placebo group n=11.

Figure 3.. bamlanivimab treatment followed by mRNA vaccination decreases the frequency of RBD MBCs in the total MBC population and reduces affinity of RBD and Spike memory B cells

(A) Scheme of study design. COVID-19-infected humans receiving bamlanivimab were immunized with mRNA vaccines between 20 and 126 days after the mAb treatment. (B-C) Frequency of Spike (B) and RBD (C) MBCs among total memory B cell population (D-E) Frequency of RBD (D) and non-RBD (E) MBCs among the Spike MBCs population (F) Affinity of RBD MBCs determined by the ratio MFI from the RBDPE-CY7/ MFI from immunoglobulin-associated beta (CD79b). (G-I) Frequency of IgG (G), IgM (H) and IgA (I) RBD MBCs Means are plotted in the graphs. An unpaired, non-parametric Mann-Whitney test was used to compare the different groups. p-values are shown in the graphs and considered significant if lower than 0.05. Sample size: treatment group n= 9, placebo group n=15

Figure 4.. Bamlanivimab treatment followed by mRNA vaccination promotes escape of class II RBD MBCs

Graphs show the Frequency of B cells binding to RBD KO constructs 24 weeks post treatment. Means are plotted in th graphs. An unpaired, non-parametric Mann-Whitney test was used to compare the different groups. p-values are shown in th graphs and considered significant if lower than 0.05. Sample size: vaccinated (treatment group n=14, placebo group n=14); unvaccinated (treatment group n=14, placebo group n=14).