Avian IgY antibodies recognize novel Dengue NS1 epitopes with the ability to neutralize Dengue 2 virus infection in vitro and in vivo

Abstract

Abstract Dengue virus (DENV) causes 96 million infections worldwide resulting in 500,000 cases of Dengue Hemorrhagic Fever (DHF) and 22,000 deaths. The severity of DENV infection is greatly enhanced by antibody dependent enhancement (ADE); increased viral load due to increased monocyte opsonization by non-neutralizing low avidity Abs from a previous infection with a different DENV serotype or secondary flavivirus infection. We have previously demonstrated that polyclonal avian anti-DENV-2 IgY ameliorates DENV infection in mice without inducing ADE. The whole polyclonal anti-DENV-2 IgY preparation contained distinct populations of IgY that recognized numerous epitopes of the envelope, membrane, and non-structural (NS) DENV proteins. We report here that two purified pools of anti-DENV-2 IgY with specificity for two different regions of NS1 had a neutralization capacity equivalent to the whole polyclonal anti-DENV-2 IgY preparation in vitro. We assayed each pool of NS1-specific IgY for the potential to induce ADE and demonstrated that neither pool induced ADE when cells were treated with IgY and challenged with a flavivirus. To determine if these NS1 specific IgY achieved neutralization via reducing vascular leakage, we utilized a trans-endothelial electrical resistance (TEER) assay. Interestingly, treatment with DENV NS1-specific IgY did not reduced vascular leakage in our model system. Final to demonstrate the therapeutic potential of NS1 specific IgY we prophylactically treated IFNAR−/− mice with 150 μg of NS1 specific IgY and saw protective efficacy up to 100% in a lethal dengue challenge. We hypothesize that the neutralizing effect of the NS1 specific IgY is via the antibody disrupting the stability of the viral replication complex.