Pregnancy enables antibody protection against intracellular infection.

Adaptive immune components are thought to exert non-overlapping roles in antimicrobial host defence, with antibodies targeting pathogens in the extracellular environment and T cells eliminating infection inside cells. Reliance on antibodies for vertically transferred immunity from mothers to babies may explain neonatal susceptibility to intracellular infections. Here we show that pregnancy-induced post-translational antibody modification enables protection against the prototypical intracellular pathogen Listeria monocytogenes.

Seroprevalence of SARS-CoV-2 infection in Cincinnati Ohio USA from August to December 2020.

The world is currently in a pandemic of COVID-19 (Coronavirus disease-2019) caused by a novel positive-sense, single-stranded RNA β-coronavirus referred to as SARS-CoV-2. Here we investigated rates of SARS-CoV-2 infection in the greater Cincinnati, Ohio, USA metropolitan area from August 13 to December 8, 2020, just prior to initiation of the national vaccination program. Examination of 9,550 adult blood donor volunteers for serum IgG antibody positivity against the SARS-CoV-2 Spike protein showed an overall prevalence of 8.

Clustering, Spatial Distribution, and Phosphorylation of Discoidin Domain Receptors 1 and 2 in Response to Soluble Collagen I.

Discoidin domain receptors (DDR1 and DDR2) are receptor tyrosine kinases that signal in response to collagen. We had previously shown that collagen binding leads to clustering of DDR1b, a process partly mediated by its extracellular domain (ECD). In this study, we investigated (i) the impact of the oligomeric state of DDR2 ECD on collagen binding and fibrillogenesis, (ii) the effect of collagen binding on DDR2 clustering, and (iii) the spatial distribution and phosphorylation status of DDR1b and DDR2 after collagen stimulation.

Fibrin and D-dimer bind to monomeric GPVI.

Fibrin has recently been shown to activate platelets through the immunoglobulin receptor glycoprotein VI (GPVI). In the present study, we show that spreading of human platelets on fibrin is abolished in patients deficient in GPVI, confirming that fibrin activates human platelets through the immunoglobulin receptor. Using a series of proteolytic fragments, we show that D-dimer, but not the E fragment of fibrin, binds to GPVI and that immobilized D-dimer induces platelet spreading through activation of Src and Syk tyrosine kinases.

Structural basis for collagen recognition by the immune receptor OSCAR.

The osteoclast-associated receptor (OSCAR) is a collagen-binding immune receptor with important roles in dendritic cell maturation and activation of inflammatory monocytes as well as in osteoclastogenesis. The crystal structure of the OSCAR ectodomain is presented, both free and in complex with a consensus triple-helical peptide (THP). The structures revealed a collagen-binding site in each immunoglobulin-like domain (D1 and D2).

Activation of glycoprotein VI (GPVI) and C-type lectin-like receptor-2 (CLEC-2) underlies platelet activation by diesel exhaust particles and other charged/hydrophobic ligands.

Platelets are activated by a range of stimuli that share little or no resemblance in structure to each other or to recognized ligands, including diesel exhaust particles (DEP), small peptides [4N1-1, Champs (computed helical anti-membrane proteins), LSARLAF (Leu-Ser-Ala-Arg-Leu-Ala-Phe)], proteins (histones) and large polysaccharides (fucoidan, dextran sulfate). This miscellaneous group stimulate aggregation of human and mouse platelets through the glycoprotein VI (GPVI)-FcR γ-chain complex and/or C-type lectin-like receptor-2 (CLEC-2) as shown using platelets from mice deficient in either or both of these receptors. In addition, all of these ligands stimulate tyrosine phosphorylation in GPVI/CLEC-2-double-deficient platelets, indicating that they bind to additional surface receptors, although only in the case of dextran sulfate does this lead to activation.

US28 is a potent activator of phospholipase C during HCMV infection of clinically relevant target cells.

Members of the cytomegalovirus family each encode two or more genes with significant homology to G-protein coupled receptors (GPCRs). In rodent models of pathogenesis, these viral encoded GPCRs play functionally significant roles, as their deletion results in crippled viruses that cannot traffic properly and/or replicate in virally important target cells. Of the four HCMV encoded GPCRs, US28 has garnered the most attention due to the fact that it exhibits both agonist-independent and agonist-dependent signaling activity and has been demonstrated to promote cellular migration and proliferation.

The carboxy-terminal tail of human cytomegalovirus (HCMV) US28 regulates both chemokine-independent and chemokine-dependent signaling in HCMV-infected cells.

The human cytomegalovirus (HCMV)-encoded G-protein-coupled receptor (GPCR) US28 is a potent activator of a number of signaling pathways in HCMV-infected cells. The intracellular carboxy-terminal domain of US28 contains residues critical for the regulation of US28 signaling in heterologous expression systems; however, the role that this domain plays during HCMV infection remains unknown. For this study, we constructed an HCMV recombinant virus encoding a carboxy-terminal domain truncation mutant of US28, FLAG-US28/1-314, to investigate the role that this domain plays in US28 signaling.

Activation of intracellular signaling pathways by the murine cytomegalovirus G protein-coupled receptor M33 occurs via PLC-{beta}/PKC-dependent and -independent mechanisms.

The presence of numerous G protein-coupled receptor (GPCR) homologs within the herpesvirus genomes suggests an essential role for these genes in viral replication in the infected host. Such is the case for murine cytomegalovirus (MCMV), where deletion of the M33 GPCR or replacement of M33 with a signaling defective mutant has been shown to severely attenuate replication in vivo. In the present study we utilized a genetically altered version of M33 (termed R131A) in combination with pharmacological inhibitors to further characterize the mechanisms by which M33 activates downstream signaling pathways.

An improved Western blot assay to assess the clearance of prion protein from plasma-derived therapeutic proteins.

Specific detection of the pathogenic prion protein, PrP(Sc), is essential for determining the prion clearance capacity of purification processes for therapeutic proteins. Use of a previously described indirect (two-antibody) Western blot assay sometimes resulted in the appearance of non-specific protein bands that interfered with the detection of small amounts of PrP(Sc)-specific signal, limiting the amount of clearance that could be determined for steps so affected. It is shown that these non-specific signals are due to the interaction between immunoglobulin fragments in the sample and the secondary antibody used in the assay.

Solvent-dependent precipitation of prion protein.

The misfolded isoform of the prion protein (PrP(Sc)) possesses many unusual physiochemical properties. Previously, we and others reported on the differential partitioning of PrP(Sc) from plasma derived therapeutic proteins during their purification processes. To understand the driving force behind these partitioning differences, we investigated the effects of various solvent conditions on the precipitation of PrP(Sc).