Selection of appropriate immunogens with requisite immunogenicity is critical towards Human Immunodeficiency Virus type 1 (HIV-1) vaccine development efforts. HIV envelope (ENV) proteins are envisioned to be used therapeutically as immunogens mimicking viral envelope proteins thereby eliciting broad neutralizing antibody response. We have demonstrated successful expression and development of a non-affinity platform downstream process for several ENV proteins that bind CD4 binding site lineage mAbs in collaboration with Duke Human Vaccine Institute and the Division of AIDS. These ENV proteins are heavily glycosylated with up to 30 sites for <i>N</i>-linked glycosylation which play a major role in hiding highly immunogenic epitopes. An observed difference in binding potency to CD4 binding site lineage mAbs suggests presence of optimal antigenicity in a subpopulation with suitable glycosylation profile. Multiple bioreactor conditions such as feeding regimes, media supplementation and waste metabolite accumulation can typically impact glycosylation profile. Lectin mediated affinity capture can potentially be employed for these ENV proteins by specifically binding to correctly glycosylated structures. Plant derived lectin products suffer from lot to lot variability due to their complex structure therefore making their use in scalable processes difficult. Our collaborators, GlycoSeLect, have demonstrated prokaryotic expression of recombinant lectins with varying specificities at high expression levels mitigating the risks associated with plant derived lectins. In this work, we present an evaluation of immobilized Recombinant Prokaryotic Lectins (RPLs) for capture of HIV-1 gp120 variants. An initial screening of these RPLs using biolayer interferometry based on Fortebio™ Octet® platform was used to determine selectivity of RPL candidates. The performance of chosen RPLs was further assessed for capture of gp120 variants from undiluted bioreactor harvest using column chromatography. Immobilized RPLs demonstrated comparable performance to developed non-affinity capture process with regards to step yield and host cell protein levels. Subtle variations in observed potency was linked to respective RPL specificity. With several constructs of HIV vaccine candidates under investigation, RPL based capture can provide researchers a simplified tool for accelerated proof of concept studies without investing dedicated efforts towards a non-affinity downstream platform development.

Recombinant prokaryotic lectins for affinity capture of HIV envelope proteins

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.