Figure 5.

Resistance of the Delta-Omicron recombinant and P337L or E340X-mutated viruses to vaccine-elicited polyclonal antibodies

(A) Neutralizing antibody titers of participants with or without previous history of SARS-CoV-2 infection and/or vaccination were measured using pseudotyped viruses with D614G, Delta, Omicron, and Delta-Omicron spike. Sera were collected from study participants pre-vaccination, 1-month post-second vaccination with Pfizer BNT162b2, and 1-month post-boost (third vaccination). Study participants were without previous SARS-CoV-2 infection (unexperienced) (left) (n = 9) or previously infected (experienced) (right) (n = 7). COVID-19 history was determined by symptoms and a PCR-positive test or serology. Equivalent amounts of D614G, Delta, Omicron, and Delta-Omicron spike protein-pseudotyped viruses were mixed with a 2-fold serial dilution of donor serum and then applied to ACE2.293T cells. Luciferase activity was measured two days post-infection. Each serum dilution was measured in triplicate and the experiment was done twice with similar results. Half-maximal inhibitory concentrations (IC50) are shown for one representative experiment. Mean values for each group are shown above the bar.

(B) Neutralizing antibody titers of sera from COVID-19 unexperienced individuals (n = 5) collected 1 month after second vaccination against D614G (as a backbone) and P337L, E340A, E340D, E340K, and E340V point mutated spike protein-pseudotyped viruses. Statistical significance was calculated by two-sided testing. (one-way ANOVA with Tukey’s multiple comparison test, ∗p ≤ 0.05, ∗∗∗p ≤ 0.001, ∗∗∗∗p ≤ 0.0001, ns: not significant). Bars are shown as mean with SD. (see also Tables S3 and S4).