Maturation of Borna disease virus glycoprotein

The maturation of Borna disease virus (BDV) glycoprotein GP was studied in regard to intracellular compartmentalization, compartmentalization signal-domains, proteolytic processing, and packaging into virus particles. Our data show that BDV-GP is (i) predominantly located in the endoplasmic reticulum (ER), (ii) partially exists in the ER already as cleaved subunits GP-N and GP-C, (iii) is directed to the ER/cis-Golgi region by its transmembrane and/or cytoplasmic domains in CD8-BDV-GP hybrid constructs and (iv) is incorporated in the virus particles as authentic BDV glycoprotein exclusively in the cleaved form decorated with N-glycans of the complex type. Downregulation of BDV-glycoproteins on the cell surface, their limited proteolytic processing, and protection of antigenic epitopes on the viral glycoproteins by host-identical N-glycans are different strategies for persistent virus infections.     

The cell surface receptor G6b, a member of the immunoglobulin superfamily, binds heparin

The G6b gene, located in the human Major Histocompatibility Complex, encodes a receptor of the immunoglobulin (Ig) superfamily. In this study, we show using a variety of techniques that the extracellular domain of the G6b protein, containing a single Ig-like domain, binds to heparin with high affinity. In an ELISA assay, this binding was displaceable with soluble heparin with an IC50 value of approximately 0.5 microg/ml. Other sulfated glycans showed weaker or no competition. The observed interaction between G6b and heparin is strongly salt dependent suggesting a mainly electrostatic interaction. Heparin might modulate the interaction of G6b with its as yet unidentified protein ligand.     

Structure of the house dust mite allergen Der f 2: implications for function and molecular basis of IgE cross-reactivity

The X-ray structure of the group 2 major allergen from Dermatophagoides farinae (Der f 2) was determined to 1.83 A resolution. The overall Der f 2 structure comprises a single domain of immunoglobulin fold with two anti-parallel beta-sheets. A large hydrophobic cavity is formed in the interior of Der f 2. Structural comparisons to distantly related proteins suggest a role in lipid binding. Immunoglobulin E (IgE) cross-reactivity between group 2 house dust mite major allergens can be explained by conserved surface areas representing IgE binding epitopes.     

蚀斑减少中和试验检测抗天花免疫球蛋白效价

为了建立测定抗天花免疫球蛋白效价的检测方法,采用抗天花免疫球蛋白50%中和100PFU痘苗病毒的稀释度来确定其效价。通过与NIBSC提供的抗天花人免疫球蛋白标准品进行的对比试验,结果显示基本一致,证明该方法是可行的。     

The amyloid fibrils of the constant domain of immunoglobulin light chain

Light chain-associated (AL) amyloidosis is characterized by dominant fibril deposition of the variable domain (VL) of an immunoglobulin light chain, and thus its constant domain (CL) has been considered not to be amyloidogenic. We examined the in vitro fibril formation of the isolated CL in comparison with β₂-microglobulin (β2-m), an immunoglobulin domain-like amyloidogenic protein responsible for dialysis-related amyloidosis. Two methods useful for β2-m at neutral pH also induced amyloid fibrils of CL, which were monitored by thioflavin-T binding and electron microscopy (EM). These results suggest that CL plays an important role, more than previously assumed, in the development of AL-amyloidosis.     

An immunostimulatory DNA sequence from a probiotic strain of Bifidobacterium longum inhibits IgE production in vitro

The immunostimulatory oligodeoxynucleotide (ODN) BL07 (5'-GCGTCGGTTTCGGTGCTCAC-3') was identified from the genomic DNA of the probiotic strain Bifidobacterium longum BB536. ODN BL07 stimulated B-lymphocyte proliferation and induced interleukin-12 (IL-12) production in macrophage-like J774.1 cells. ODNs BL07 and BL07S (modified with phosphorothioate backbone) significantly inhibited immunoglobulin E (IgE) production and stimulated interferon-gamma (IFN-gamma) and IL-12 production, but did not affect IL-4 secretion in murine splenic cells of ovalbumin-primed BALB/c mice. These ODNs also significantly inhibited production of IgE in purified murine B cells in the presence of IL-4 and anti-CD40. The results suggest the potential of ODNs BL07 and BL07S in preventing IgE-related immune responses and the possible involvement of ODN BL07 in the antiallergic efficacy of B. longum BB536.     

Structure of the Epstein-Barr virus oncogene BARF1

The Epstein-Barr virus is a human gamma-herpesvirus that persistently infects more than 90% of the human population. It is associated with numerous epithelial cancers, principally undifferentiated nasopharyngeal carcinoma and gastric carcinoma. The BARF1 gene is expressed in a high proportion of these cancers. An oncogenic, mitogenic and immortalizing activity of the BARF1 protein has been shown. We solved the structure of the secreted BARF1 glycoprotein expressed in a human cell line by X-ray crystallography at a resolution of 2.3A. The BARF1 protein consists of two immunoglobulin (Ig)-like domains. The N-terminal domain belongs to the subfamily of variable domains whereas the C-terminal one is related to a constant Ig-domain. BARF1 shows an unusual hexamerisation involving two principal contacts, one between the C-terminal domains and one between the N-terminal domains. The C-terminal contact with an uncommonly large contact surface extends the beta-sandwich of the Ig-domain through the second molecule. The N-terminal contact involves Ig-domains with an unusual relative orientation but with a more classical contact surface with a size in the range of dimer interactions of Ig-domains. The structure of BARF1 is most closely related to CD80 or B7-1, a co-stimulatory molecule present on antigen presenting cells, from which BARF1 must have been derived during evolution. Still, domain orientation and oligomerization differ between BARF1 and CD80. It had been shown that BARF1 binds to hCSF-1, the human colony-stimulating factor 1, but this interaction has to be principally different from the one between CSF-1 and CSF-1 receptor.     

Molecular cloning and gene expression of endoplasmic reticulum stress proteins in Japanese monkey, Macaca fuscata

BACKGROUND: Immunoglobulin heavy-chain binding protein (BiP), calreticulin (Crt), and protein disulfide isomerase (PDI), are major resident endoplasmic reticulum (ER) stress proteins which are involved in diverse roles relating to successful folding, assembly, intracellular localization, and degradation of other proteins. METHODS: In this study, we molecular cloned cDNAs for BiP, Crt, and PDI from Japanese monkey (Macaca fuscata), and analyzed tissue-specific expression of respective genes. RESULTS AND CONCLUSIONS: The lengths of protein-coding regions of these cDNAs for BiP, Crt and PDI are 1965, 1254, and 1533 bp, respectively. Each protein has a signal peptide and a KDEL motif in N- and C-terminal parts respectively, showing its intracellular localization to be the lumen of the ER. These stress proteins are highly conserved, showing that their similarities among mammals are more than 90% in the level of amino acid. The expression of the genes for stress proteins differed among the monkey tissues examined. BiP and PDI gene expression was predominant in secretory tissues such as liver and kidney, and brain tissues. But Crt gene expressed rather ubiquitously in a variety of tissues.     

Two new Ig VH gene families in Oncorhynchus mykiss

Genes encoding the immunoglobulin heavy-chain variable region (Ig VH) in rainbow trout (Oncorhynchus mykiss) have been grouped into 11 families. While obtaining a baseline assessment of the various gene families utilized by trout in the production of secreted antibody, we discovered two new families. These proposed Ig VH families, Families XII and XIII, were rarely observed; only two VH sequence types were detected for each new family, suggesting that they may not be commonly used in response to antigens, or that the captive environment may not lead to typical exposures seen in the wild. Additionally, unlike preceding studies, we found at least one representative gene sequence for each of the 11 reported Ig VH gene families, possibly indicating that the repertoire of trout Ig VH gene families may be more universal among different stocks than previously realized. GenBank accession numbers: Family XII—DQ453185 and DQ453150; Family XIII—DQ453153 and DQ453146; others DQ453143, DQ453156, DQ831723, DQ831825.     

Crystal structure of the Campylobacter jejuni Cj0090 protein reveals a novel variant of the immunoglobulin fold among bacterial lipoproteins

Bacterial lipoproteins play an important role in bacterial pathogenesis and physiology. The genome of Campylobacter jejuni, a major foodborn pathogen, is predicted to contain over 20 lipoproteins. However, the functions of the majority of C. jejuni lipoproteins remain unknown. The Cj0090 protein is encoded by a lipoprotein operon composed of cj0089, cj0090, and cj0091. Here, we report the crystal structure of Cj0090 at 1.9 Å resolution, revealing a novel variant of the immunoglobulin fold with β‐sandwich architecture. The structure suggests that Cj0090 may be involved in protein‐protein interactions, consistent with a possible role for bacterial lipoproteins. Proteins 2012;. © 2012 Wiley Periodicals, Inc.