The mechanism of differential neutralization of dengue serotype 3 strains by monoclonal antibody 8A1

While previous studies have demonstrated that envelope (E) glycoprotein variation between dengue viruses (DENV) genotypes can influence antibody neutralization potency, the mechanisms of variable neutralization remain incompletely understood. Here we characterize epitope antibody interactions of a DENV-3 EDIII binding mouse mAb 8A1 which displays highly variable neutralizing activity against DENV-3 genotypes. Using a DENV-3 reverse genetics platform, we characterize ability of 8A1 to bind and neutralize naturally occurring DENV-3 E genotypic variant viruses. Introduction of single and multiple amino acid mutations into the parental clone background demonstrates that mutations at positions 301 and 383 on EDIII are responsible for 8A1 differential neutralization phenotypes. ELISA and surface plasmon resonance (SPR) studies indicate differences in binding are responsible for the variable neutralization. Variability at position 301 primarily determined binding difference through influencing antibody-EDIII dissociation rate. Our findings are relevant to many groups focusing on DENV EDIII as a vaccine target.

► We mapped the 8A1 differential neutralization to two amino acids at sites 301 and 383.
► We found that binding difference is responsible for 2/3 of the neutralization difference between DENV3 genotypes.
► We found that dissociation rate determines the binding difference between 8A1 and DENV3 viruses.
► We found that site 301 determines the dissociation rate of 8A1 binding to DENV3 viruses.