Spike recognition and neutralization of SARS-CoV-2 Omicron subvariants elicited after the third dose of mRNA vaccine

Humoral Responses against BQ.1.1 Elicited after Breakthrough Infection and SARS-CoV-2 mRNA Vaccination

“…For the BQ.1.1 S, at the M4-Va3 timepoint donors with recent BTI better recognized the S than individuals with no recent infection, and this difference in recognition was more significant four weeks after the fourth dose ( Figure 1 C). The level of BQ.1.1 S recognition was significantly lower compared to D614G S in donors without recent BTI ( Figure 1 D), in agreement with recent reports [ 4 , 5 ]. In donors who had recently been infected, there was a significant but smaller difference in the level of recognition between the two Spikes compared to the other group.…”

“…Pre-pandemic plasma samples were used as negative controls in cytometry assays (data not shown). The conformationally independent S2-specific monoclonal antibody CV3-25 was used as a positive control and to normalize Spike expression in flow cytometry assays, as described [ 4 , 26 , 27 , 28 , 29 ]. Alexa Fluor-647-conjugated goat anti-human antibodies (Abs) able to detect all Ig isotypes (anti-human IgM, IgG, IgA; Jackson ImmunoResearch Laboratories, Cat # 109-605-064) were used as secondary Abs to detect plasma binding in flow cytometry experiments.…”

“…The plasmids encoding the SARS-CoV-2 D614G and BQ.1.1 Spike variants were previously described [ 4 ]. The pNL4.3 R-E-Luc plasmid was obtained from the NIH AIDS Reagent Program (Cat# 3418).…”

“…Samples were acquired on a LSRFortessa cytometer (BD Biosciences, Franklin Lakes, NJ, USA), and data analysis was performed using FlowJo v10.7.1 (Tree Star). The conformationally independent anti-S2 antibody CV3-25, effective against all Spike variants, was used to normalize Spike expression, as reported [ 4 , 26 , 28 , 29 ]. The Median Fluorescence intensities (MFI) obtained with plasma were normalized to the MFI obtained with CV3-25 and presented as percentage of CV3-25 binding.…”

“…The Omicron BQ.1.1 variant is a sublineage of the BA.5 variant that spreads very rapidly and is now the major circulating lineage in several countries [ 1 , 2 ]. Recent studies have shown that original SARS-CoV-2 mRNA vaccines, based on the ancestral Wuhan strain Spike (S), lead to poor humoral responses against several Omicron subvariants, including the BQ.1.1 variant [ 3 , 4 , 5 ]. With the goal to improve immune responses against these subvariants, Moderna and Pfizer bivalent vaccines have recently been approved by health authorities in many countries [ 6 , 7 , 8 ].…”