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Smider, Vaughn V.

Publications and source records attributed to Smider, Vaughn V..

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The smallest functional antibody fragment: Ultralong CDR H3 antibody knob regions potently neutralize SARS-CoV-2

Cows produce antibodies with a disulfide-bonded antigen-binding domain embedded within ultralong heavy chain third complementarity determining regions. This “knob” domain is analogous to natural cysteine-rich peptides such as knottins in that it is small and stable but can accommodate diverse loops and disulfide bonding patterns. We immunized cattle with SARS-CoV-2 spike and found ultralong CDR H3 antibodies that could neutralize several viral variants at picomolar IC 50 potencies in vitro and could protect from disease in vivo. The independent CDR H3 peptide knobs were expressed and maintained the properties of the parent antibodies. The knob interaction with SARS-CoV-2 spike was revealed by electron microscopy, X-ray crystallography, NMR spectroscopy, and mass spectrometry and established ultralong CDR H3-derived knobs as the smallest known recombinant independent antigen-binding fragment. Unlike other vertebrate antibody fragments, these knobs are not reliant on the immunoglobulin domain and have potential as a new class of therapeutics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Structural basis of broad HIV neutralization by a vaccine-induced cow antibody

Potent broadly neutralizing antibodies (bnAbs) to HIV have been very challenging to elicit by vaccination in wild-type animals. Here, by x-ray crystallography, cryo–electron microscopy, and site-directed mutagenesis, we structurally and functionally elucidate the mode of binding of a potent bnAb (NC-Cow1) elicited in cows by immunization with the HIV envelope (Env) trimer BG505 SOSIP.664. The exceptionally long (60 residues) third complementarity-determining region of the heavy chain (CDR H3) of NC-Cow1 forms a mini domain (knob) on an extended stalk that navigates through the dense glycan shield on Env to target a small footprint on the gp120 CD4 receptor binding site with no contact of the other CDRs to the rest of the Env trimer. These findings illustrate, in molecular detail, how an unusual vaccine-induced cow bnAb to HIV Env can neutralize with high potency and breadth.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Conservation and diversity in the ultralong third heavy-chain complementarity-determining region of bovine antibodies

Antibodies provide a broad defense against a vast array of antigens; however, the structural features that contribute to this diverse antigen recognition vary in different vertebrates. In cows, a subset of antibodies have an exceptionally long third heavy-chain complementarity-determining region (CDR H3) that is highly variable in sequence and includes multiple cysteines. These long CDR H3s (up to 69 residues) fold into a long stalk atop which sits a knob domain that is located far from the antibody surface. We have determined crystal structures of three bovine Fabs to decipher the conserved and variable features of ultralong CDR H3s that lead to diversity in antigen recognition. Despite high sequence variability, the stalks adopt a conserved β-ribbon structure, whereas the knob regions share a conserved β sheet that serves as a scaffold for two connecting loops of variable length and conformation, as well as one conserved disulfide. Variation in patterns and connectivity of the remaining disulfides contribute to the structural diversity of the knob. Finally, the unusual architecture of these ultralong bovine CDR H3s for generating diversity is unique in adaptive immune systems and may inform efforts in antibody engineering.

60 APPLIED LIFE SCIENCES↗