Screening the interactions between HIV-1 neutralizing antibodies and model lipid surfaces.

Our work is motivated by the observation that rare, broadly neutralizing antibodies (NAbs), 4E10 and 2F5, associate with HIV-1 lipids as part of a required first step in neutralization before binding to membrane-proximal antigens. Subsequently, induction of these types of NAbs may be limited by immunologic tolerance due to autoreactivity with host cell membranes. Despite the significance of this lipid reactivity there is little experimental evidence detailing NAb-membrane interactions. Simple and efficient screening assays are needed to select antibodies that have similar lipid reactivity as known NAbs. To this end we have developed a surface plasmon resonance (SPR) spectroscopy based assay that monitors antibody binding to thiol self-assembled monolayers (SAMs) that replicate salient lipid surface chemistries and NAb binding to lipid surfaces. Specifically, we probed the relative importance of charge and hydrophobicity on antibody-surface interactions. We found that NAb binding to hydrophobic thiol surfaces was significantly greater than that of control monoclonal antibodies (mAbs). Furthermore, we confirmed the importance of charge-mediated antibody surface interactions, originally suggested by results from mAb interactions with conventional lipid vesicle/bilayer surfaces. Our approach, using self-assembled thiol monolayers that replicate the binding behavior of NAbs on lipid surfaces, thus provides an efficient and useful tool to screen interactions of mAbs and lipid-reactive NAbs.