Figure 1.

Sites of substitution mutations modeled on the dengue virus E protein.A, depicts the putative affinity-enhancing mutation sites in the three complementarity determining regions (CDRs) of scFv's primary structure (selected from our previous in silico study (30)). B, in the 3D complex model structure, the mutation sites in VH-CDR1, CDR3, and VL-CDR3 are located in close proximity to the Fu-bc epitope (orange and yellow surface, respectively). The residues that were substituted by site-directed mutagenesis are shown as blue and red sticks on the dengue virus EDII cartoon-surface structure, where the blue stick shows affinity-enhancing substitution sites (VH-CDR1: T30, D31, and Y33; VH-CDR3: G103 and Y105; VL-CDR3: S227), and the red stick shows affinity-reducing substitution sites (VH-CDR1: Y33 and VL-CDR3: H230). C, both the beneficial and detrimental substitution sites are located on the periphery of the epitope-binding site. The green surface area enclosed by the black dotted line includes residues of structural paratope of the scFv antibody. The blue and red colors include the beneficial and detrimental substitution residues, respectively. Else, the variable heavy and light chains are shown in gray and violet surface areas, respectively. EDII, envelope Domain II; Fu-bc, fusion and bc loop; scFv, single chain variable fragment antibody.