Fig. 3

S2 antibodies recognize S proteins of SARS-CoV-2 variants. A Comparative ELISA was performed by coating plates with 0.5 µg/ml recombinant S protein of indicated SARS-CoV-2 variants and incubating with B-S2-mAb-2, -5, -7, -10, -13 (100 ng/ml). EpEx and NMIgG served as negative controls. B The five B-S2-mAbs (1 µg/ml) were used as primary antibodies to detect recombinant S proteins of SARS-CoV-2 Alpha, Beta, Gamma, Delta, Omicron BA.1, BA.2 and BA.5 variants by immunoblotting under reducing conditions. C Immunoblotting under non-reducing conditions was performed to detect variants of tagged-recombinant S protein by indicated B-S2-mAbs (used at 1 µg/ml). In panels B and C, His mAb was used as a positive and loading control. D Immunofluorescence assay to detect overexpressed S protein of the indicated SARS-CoV-2 variants in HEK293T cells. The assay was performed using the five B-S2-mAbs (1 µg/ml). NMIgG served as a negative control