Characterization and immunogenicity of a novel mosaic M HIV-1 gp140 trimer.

Unlabelled: The extraordinary diversity of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) glycoprotein poses a major challenge for the development of an HIV-1 vaccine. One strategy to circumvent this problem utilizes bioinformatically optimized mosaic antigens. However, mosaic Env proteins expressed as trimers have not been previously evaluated for their stability, antigenicity, and immunogenicity.

A common solution to group 2 influenza virus neutralization.

The discovery and characterization of broadly neutralizing antibodies (bnAbs) against influenza viruses have raised hopes for the development of monoclonal antibody (mAb)-based immunotherapy and the design of universal influenza vaccines. Only one human bnAb (CR8020) specifically recognizing group 2 influenza A viruses has been previously characterized that binds to a highly conserved epitope at the base of the hemagglutinin (HA) stem and has neutralizing activity against H3, H7, and H10 viruses. Here, we report a second group 2 bnAb, CR8043, which was derived from a different germ-line gene encoding a highly divergent amino acid sequence.

Sensitive and specific detection of the non-human sialic Acid N-glycolylneuraminic acid in human tissues and biotherapeutic products.

Background: Humans are genetically defective in synthesizing the common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc), but can metabolically incorporate it from dietary sources (particularly red meat and milk) into glycoproteins and glycolipids of human tumors, fetuses and some normal tissues. Metabolic incorporation of Neu5Gc from animal-derived cells and medium components also results in variable contamination of molecules and cells intended for human therapies. These Neu5Gc-incorporation phenomena are practically significant, because normal humans can have high levels of circulating anti-Neu5Gc antibodies.

Human-specific expression of Siglec-6 in the placenta.

CD33-related-Siglecs are lectins on immune cells that recognize sialic acids via extracellular domains, and deliver negative signals via cytosolic tyrosine-based regulatory motifs. We report that while Siglec-6/OB-BP1 (which can also bind leptin) is expressed on immune cells of both humans and the closely related great apes, placental trophoblast expression is human-specific, with little or no expression in ape placentae. Human-specific transcription factor recognition site changes in the Siglec-6 promoter region can help explain the human-specific expression.

GlycoPEGylation of recombinant therapeutic proteins produced in Escherichia coli.

Covalent attachment of polyethylene glycol, PEGylation, has been shown to prolong the half-life and enhance the pharmacodynamics of therapeutic proteins. Current methods for PEGylation, which rely on chemical conjugation through reactive groups on amino acids, often generate isoforms in which PEG is attached at sites that interfere with bioactivity. Here, we present a novel strategy for site-directed PEGylation using glycosyltransferases to attach PEG to O-glycans.

Human-specific regulation of alpha 2-6-linked sialic acids.

Many microbial pathogens and toxins recognize animal cells via cell surface sialic acids (Sias) that are alpha 2-3- or alpha 2-8-linked to the underlying glycan chain. Human influenza A/B viruses are unusual in preferring alpha 2-6-linked Sias, undergoing a switch from alpha 2-3 linkage preference during adaptation from animals to humans. This correlates with the expression of alpha 2-6-linked Sias on ciliated human airway epithelial target cells and of alpha 2-3-linked Sias on secreted soluble airway mucins, which are unable to inhibit virus binding.

CD33/Siglec-3 binding specificity, expression pattern, and consequences of gene deletion in mice.

Mouse CD33/Siglec-3 (mCD33) is the apparent ortholog of human CD33/Siglec-3 (hCD33), a member of the Siglec (sialic acid-binding Ig superfamily lectin) family of sialic acid-recognizing cell-surface lectins. We examined the binding specificity and expression pattern of mCD33 and explored its functions by generating mice deficient in this molecule. Like hCD33, mCD33 is expressed on myeloid precursors in the bone marrow, albeit mostly in the more mature stages of the granulocytic lineage.