DNA-delivered antibody cocktail exhibits improved pharmacokinetics and confers prophylactic protection against SARS-CoV-2.

Monoclonal antibody therapy has played an important role against SARS-CoV-2. Strategies to deliver functional, antibody-based therapeutics with improved in vivo durability are needed to supplement current efforts and reach underserved populations. Here, we compare recombinant mAbs COV2-2196 and COV2-2130, which compromise clinical cocktail Tixagevimab/Cilgavimab, with optimized nucleic acid-launched forms. Functional profiling of in vivo-expressed, DNA-encoded monoclonal antibodies (DMAbs) demonstrated similar specificity, broad antiviral potency and equivalent protective efficacy in multiple animal challenge models of SARS-CoV-2 prophylaxis compared to protein delivery. In PK studies, DNA-delivery drove significant serum antibody titers that were better maintained compared to protein administration. Furthermore, cryo-EM studies performed on serum-derived DMAbs provide the first high-resolution visualization of in vivo-launched antibodies, revealing new interactions that may promote cooperative binding to trimeric antigen and broad activity against VoC including Omicron lineages. These data support the further study of DMAb technology in the development and delivery of valuable biologics.

Multiple approaches converge on the structure of the integrin alphaIIb/beta3 transmembrane heterodimer.

Integrins link the cytoskeleton to the extracellular matrix and regulate key signaling events that coordinate cellular processes such as secretion, migration, and proliferation. A single integrin molecule can exist in a resting state that does not bind extracellular ligands or in an active state that can engage ligands and form large signaling complexes. Activation signals are transduced between the cytosolic region and the extracellular region by a binary on/off switch in the integrin's transmembrane (TM) domain; the integrin's alpha and beta subunits each have a single TM helix that forms an alpha/beta heterodimer in the resting state, and the TM heterodimer separates to transduce an activation signal across the membrane. In this article, two methods used to generate models of the TM heterodimer, both converging on the same structure, are described. The first model was generated by a Monte Carlo algorithm that selected conformations based on their agreement with published experimental mutagenesis results. The second model was generated by threading the integrin's sequence onto TM helix dimers parsed from the Protein Data Bank and by selecting conformations based on their agreement with published experimental cysteine crosslinking results. The two models have similar structures; however, they differ markedly from some previously published models. To distinguish conformations that reflect the native integrin, we compared the Monte Carlo model, the threaded model, and four published models with experimental mutagenesis and cysteine crosslinking results. The models presented here had high correlation coefficients when compared with experimental findings, and they are in excellent agreement, both in terms of accuracy and in terms of precision, with a recent NMR structure. These results demonstrate that multiple approaches converged on the same structure of the resting integrin's TM heterodimer, and this conformation likely reflects the integrin's native structure.