Figure 1.

The ⁶¹¹LY⁶¹² mutation in the antibody-dependent enhancement (ADE) domain leads to aberrant glycosylation of the SARS-CoV-2 spike (S) protein

(A) Amino acid sequences of the wild type (WT) and mutants close to the putative ADE domain of the SARS-CoV-2 spike protein. Red: ADE domain; Blue: mutation sites.

(B) BHK21 cells were transfected with plasmid DNA to introduce full-length (FL) spike protein expression and then infected with the recombinant VSV defective in glycoprotein expression (VSVΔG-GFP/G) for pseudovirus production. Spike protein expression in cells at 24 h post-transfection and in S pseudovirus (S_pp) in the culture supernatant at 16 h post-VSVΔG-GFP/G infection was examined by immunoblotting.

(C) Assessment of S protein glycosylation in S_pp via immunoblot after treatment with peptide N-glycosidase F (PNGase F).

(D) Quantification of the S_pp titer via counting the GFP-positive BHK21-hACE2 cells at 16 h post-infection.

(E and F) 293T cells were used to express the LYQD-related S mutant protein and generate the mutant S_pp. The protein expression in cell and in S_pp was detected by immunoblotting (E), and the S_pp titer was measured in BHK21-hACE2 cells (F). ∗∗p < 0.01. Error bars represent SEM and n = 3.