The B7 homolog butyrophilin BTN2A1 is a novel ligand for DC-SIGN

The MHC-encoded butyrophilin, BTN2A1, is a cell surface glycoprotein related to the extended family of B7 costimulatory molecules. BTN2A1 mRNA was expressed in most human tissues, but protein expression was significantly lower in leukocytes. An Ig-fusion protein of BTN2A1 bound to immature monocyte-derived dendritic cells. Binding diminished upon MoDC maturation and no binding was detected to Langerhans cells. Induction of the counterreceptor was IL-4 dependent and occurred early during dendritic cell differentiation. The interaction required the presence of Ca2+ and was mediated by high-mannose oligosaccharides. These properties matched DC-SIGN, a DC-specific HIV-1 entry receptor. This was confirmed by binding of soluble BTN2A1 to DC-SIGN-transfectants and its inhibition by a specific Ab. DC-SIGN bound to native BTN2A1 expressed on a range of tissues. However, BTN2A1 was not recognized on some normal cells such as HUVECs despite a similar expression level. The BTN2A1 of tumor cells such as HEK293T have more high-mannose moieties in comparison to HUVECs, and those high-mannose moieties are instrumental for binding to DC-SIGN. The data are consistent with tumor- or tissue-specific glycosylation of BTN2A1 governing recognition by DC-SIGN on immature monocyte-derived dendritic cells.     

Increased efficiency of Campylobacter jejuni N-oligosaccharyltransferase PglB by structure-guided engineering

Conjugate vaccines belong to the most efficient preventive measures against life-threatening bacterial infections. Functional expression of N-oligosaccharyltransferase (N-OST) PglB of Campylobacter jejuni in Escherichia coli enables a simplified production of glycoconjugate vaccines in prokaryotic cells. Polysaccharide antigens of pathogenic bacteria can be covalently coupled to immunogenic acceptor proteins bearing engineered glycosylation sites. Transfer efficiency of PglB_Cj is low for certain heterologous polysaccharide substrates. In this study, we increased glycosylation rates for Salmonella enterica sv. Typhimurium LT2 O antigen (which lacks N-acetyl sugars) and Staphylococcus aureus CP5 polysaccharides by structure-guided engineering of PglB. A three-dimensional homology model of membrane-associated PglB_Cj, docked to the natural C. jejuni N-glycan attached to the acceptor peptide, was used to identify potential sugar-interacting residues as targets for mutagenesis. Saturation mutagenesis of an active site residue yielded the enhancing mutation N311V, which facilitated fivefold to 11-fold increased in vivo glycosylation rates as determined by glycoprotein-specific ELISA. Further rounds of in vitro evolution led to a triple mutant S80R-Q287P-N311V enabling a yield improvement of S. enterica LT2 glycoconjugates by a factor of 16. Our results demonstrate that bacterial N-OST can be tailored to specific polysaccharide substrates by structure-guided protein engineering.     

High resolution array in the clinical approach to chromosomal phenotypes

Array genomic hybridization (AGH) has recently been implemented as a diagnostic tool for the detection of submicroscopic copy number variants (CNVs) in patients with developmental disorders. However, there is no consensus regarding the choice of the platform, the minimal resolution needed and systematic interpretation of CNVs. We report our experience in the clinical diagnostic use of high resolution AGH up to 100 kb on 131 patients with chromosomal phenotypes but previously normal karyotype. We evaluated the usefulness in our clinics and laboratories by the detection rate of causal CNVs and CNVs of unknown clinical significance and to what extent their interpretation would challenge the systematic use of high-resolution arrays in clinical application. Prioritizing phenotype-genotype correlation in our interpretation strategy to criteria previously described, we identified 33 (25.2%) potentially pathogenic aberrations. 16 aberrations were confirmed pathogenic (16.4% syndromic, 8.5% non-syndromic patients); 9 were new and individual aberrations, 3 of them were pathogenic although inherited and one is as small as approx 200 kb. 13 of 16 further CNVs of unknown significance were classified likely benign, for 3 the significance remained unclear. High resolution array allows the detection of up to 12.2% of pathogenic aberrations in a diagnostic clinical setting. Although the majority of aberrations are larger, the detection of small causal aberrations may be relevant for family counseling. The number of remaining unclear CNVs is limited. Careful phenotype-genotype correlations of the individual CNVs and clinical features are challenging but remain a hallmark for CNV interpretation.     

GUS expression in sweet oranges (Citrus sinensis L. Osbeck) driven by three different phloem-specific promoters

Huanglongbing (HLB) is associated with Candidatus Liberibacter spp., endogenous, sieve tube-restricted bacteria that are transmitted by citrus psyllid insect vectors. Transgenic expression in the phloem of specific genes that might affect Ca. Liberibacter spp. growth and development may be an adequate strategy to improve citrus resistance to HLB. To study specific phloem gene expression in citrus, we developed three different binary vector constructs with expression cassettes bearing the β-glucuronidase (GUS) reporter gene (uidA) under the control of one of the three different promoters: Citrus phloem protein 2 (CsPP2), Arabidopsis thaliana phloem protein 2 (AtPP2), and Arabidopsis thaliana sucrose transporter 2 (AtSUC2). Transgenic lines of ‘Hamlin’, ‘Pera’, and ‘Valencia’ sweet oranges [Citrus sinensis (L.) Osbeck] were produced via Agrobacterium tumefaciens transformation. The epicotyl segments collected from in vitro germinated seedlings were used as explants. The gene nptII, which confers resistance to the antibiotic kanamycin, was used for selection. The transformation efficiency was expressed as the number of GUS-positive shoots over the total number of explants and varied from 1.54 to 6.08?% among the three cultivars and three constructs studied. Several lines of the three sweet orange cultivars analyzed using PCR and Southern blot analysis were genetically transformed with the three constructs evaluated. The histological GUS activity in the leaves indicates that the uidA gene was preferentially expressed in the phloem, which suggests that the use of the three promoters might be adequate for producing HLB-resistant transgenic sweet oranges. The results reported here conclusively demonstrate the preferential expression of GUS in the phloem driven by two heterologous and one homologous gene promoters. Key message The results reported here conclusively demonstrate the preferential expression of GUS in the phloem driven by two heterologous and one homologous gene promoters.     

Technology and Affect: HIV/AIDS Testing in Brazil

Contemporary techno-scientific and medical developments are restructuring social interactions and the very processes by which individual subjectivity is formed. This essay elaborates on the experiential and ethical impact of such transformations from the perspective of people who, in ordinary and unexpected ways, act science and technology out. We carried out ethnographic research in an HIV/AIDS Testing and Counseling Center (CTA) in northeastern Brazil, combining participant observation with epidemiological analyses and clinical survey. We found a high demand for free testing by low-risk clients, largely working and middle class, experiencing anxiety and complaining of AIDS-like symptoms. Most of the clients were sero-negative and many returned for a second and third testing. We understand this to be a new techno-cultural phenomenon and call it imaginary AIDS. Throughout this essay, we describe CTA's routine practices, place these practices in historical, political, economic and cross-cultural perspective, and analyze the subjective data we collected from the clients of our pilot study. We explore how clinical epidemiological expertise and HIV testing technology are integrated into new forms of bio-politics aimed at specific marketable and disease-free populations, and on the affective absorption of bio-technical truth and the engendering of a technoneurosis in this testing center.     

Rabies neutralizing antibody detection by indirect immunperoxidase serum neutralization assay performed on chicken embryo related cell line

The aim of this study was to evaluate the indirect immunoperoxidase virus neutralization (IPVN) and mouse neutralization test (MNT) to detect antibodies against rabies virus from vaccinated dogs and cattle. The IPVN was set up for the ability to measure 0.5 International Units/ml (IU) of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. IPVN was developed and standardized in chicken embryo related (CER) cell line when 141 dog and 110 cattle sera were applied by serial five-fold dilutions (1:5, 1:25, 1:125) as well as the positive and negative reference controls, all added in four adjacent wells, of 96-well microplates. A 50 microl amount of CVS32 strain dilution containing 50-200 TCID50/ml was mixed to each serum dilution, and after 90 min 50 microl of 3 x 10(5) cells/mlcell suspension added to each well. After five days of incubation, the monolayers were fixed and the IPVN test performed. The correlation coefficient between the MNT and IPVN performed in CER cells was r = 0.9949 for dog sera (n = 100) and r = 0.9307 for cattle sera (n = 99), as well as good specificity (94.7%), sensitivity (87.5%), and agreement (96.6%) were also obtained. IPVN technique can adequately identify vaccinated and unvaccinated animals, even from low-responding vaccinated animals, with the advantage of low cost and faster then MNT standard test.     

Functionalization of glucose at position C-3 for transition metal coordination: organo-rhenium complexes with carbohydrate skeletons

Novel 3-O-[1,2;5,6-di-O-isopropylidene-alpha-D-glucofuranose] and 3-O-[D-glucose] derivatives with an iminodiacetate (N,O,O), a histidinate, and an N-(acetetyl)picolylamine (N,N,O) chelating system for tridentate coordination of the organometallic M(CO)(3)-fragment (M = Tc, Re) have been prepared. The chelates were introduced and assembled through reductive amination starting from 3-O-[1,2;5,6-di-O-isopropylidene-alpha-D-glucofuranose]-acetaldehyde. After deprotection, the pyranose derivatives were reacted with the precursor [NEt(4)](2)[ReBr(3)(CO)(3)] to afford the corresponding organometallic complexes in yields between 54% and 94%. The NMR, MS, and IR analyses corroborated the tridentate coordination of the organometallic metal center exclusively via the synthetic chelates. In the case of the N-(acetyl)picolylamine derivative, the coordinative properties were further confirmed by X-ray structure analysis of the first Re(CO)(3)-D-glucofuranose complex. All glucose complexes unveiled good stability and solubility in organic and aqueous media.     

Nitrite as the major source of nitric oxide production by Arabidopsis thaliana in response to Pseudomonas syringae

The origin of nitric oxide (*NO) in plants is unclear and an *NO synthase (NOS)-like enzyme and nitrate reductase (NR) are claimed as potential sources. Here we used wild-type and NR-defective double mutant plants to investigate *NO production in Arabidopsis thaliana in response to Pseudomonas syringae pv maculicola. NOS activity increased substantially in leaves inoculated with P. syringae. However, electron paramagnetic resonance experiments showed a much higher *NO formation that was dependent on nitrite and mitochondrial electron transport rather than on arginine or nitrate. Overall, these results indicate that NOS, NR and a mitochondrial-dependent nitrite-reducing activity cooperate to produce *NO during A. thaliana-P. syringae interaction.     

Plasmodium berghei parasite transformed with green fluorescent protein for screening blood schizontocidal agents

High priority has been given to new assays that facilitate and accelerate the development of novel antimalarial compounds. Unlike evaluation of drugs in vitro, in which new approaches have been used to expedite identification of parasites, the conventional in vivo murine assay requires determination of parasitemia by light microscopy, an incompatible technique to test large numbers of drugs. We have investigated the possibility of using an autonomously fluorescent Plasmodium berghei strain, stably transformed with the green fluorescent protein, to rapidly quantify parasite growth by flow cytometry. The major improvement of this method is that P. berghei line transformed with green fluorescent protein parasites can be quickly and specifically detected in a drop of parasite-infected blood without any manipulation of the sample. Our results showed a clear correlation between the numbers of fluorescent cells detected by flow cytometry and conventional parasitemia, including a correspondence in the peaks of parasitemia. The validation of P. berghei line transformed with green fluorescent protein for chemotherapy studies was performed by evaluating its response to conventional antimalarial drugs such as chloroquine, quinine and sodium artesunate. The results of drug-susceptibility assays as determined by flow cytometry were comparable with those obtained by microscopic examination of Giemsa-stained slides. This PbGFP parasite should prove to be a rapid, simple and sensitive tool for the examination of the large number of compounds and conditions involved in the initial stages of drug development.