Thwarting HIV evasion of antibody avidity with novel antibody architectures

Abstract

Despite decades of effort, no current vaccine elicits neutralizing antibodies at concentrations blocking HIV infection. In addition to structural features of HIV's envelope spike that facilitate antibody evasion, a hypothesis for the ineffective immune response lies in the low density and limited mobility of HIV envelope spikes, which impedes bivalent binding by antibodies, reducing avidity, minimizing the potential for high affinity binding and virus neutralization. We intend to engineer anti-HIV reagents that bind with high avidity to single spikes, overcoming potential problems with the low density of HIV spikes. Here, we demonstrate a strategy to use dsDNA as a rigid molecular ruler to map epitopes on the HIV envelope protein to gain insight into the relatively unknown spatial environment of the spike trimer. Upon determining the optimal separation distance between epitopes, the dsDNA linker will be replaced with a structured protein linker. This technique should allow for the development of a novel multivalent antibody reagent improving binding and increasing avidity. Optimal HIV binding proteins will be trimerized by attaching a trimerization motif, reducing the concentration required for sterilizing immunity. To date, we have several bispecific DNA reagents that have the ability to neutralize various strains of HIV with greater potency than its individual components. These results demonstrate the promise for discovery of optimal anti-HIV reagents using this technology.

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