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. 2020 Dec 13;8(4):758. doi: 10.3390/vaccines8040758

Figure 2.

Figure 2

Binding of purified VHHs to optC.664 gp140 SOSIP at acidic pH. Binding experiments were performed using 250 ng of VHHs 5, 9, 28 and A6 [29] and 200 ng immobilized optC.664 gp140 SOSIP at pH 4.2 (a) and pH 3.7 (b). Binding of VHHs was detected by ELISA via their C-terminal myc-tag. Binding efficiency of VHHs at acidic pH (blue/pink filled bars, respectively) was compared to binding at pH 7.4 (green bars). Full human mAb b12 was included for comparison (detection with α-human IgG-HRP). SOSIP pretreated at acidic pH for 1 h was used as control for antigen integrity (spotted bars). α-c myc and α-human IgG antibodies represent controls without addition of VHHs. Error bars represent SEM of duplicates from three experiments. Statistical differences in absorption between pH 7.4 and acidic pH were determined using t-test. ***: p < 0.001, **: p < 0.01; *: p < 0.05.