Epitope Tags beside the N-Terminal Cytoplasmic Tail of Human BST-2 Alter Its Intracellular Trafficking and HIV-1 Restriction

BST-2 blocks the particle release of various enveloped viruses including HIV-1, and this antiviral activity is dependent on the topological arrangement of its four structural domains. Several functions of the cytoplasmic tail (CT) of BST-2 have been previously discussed, but the exact role of this domain remains to be clearly defined. In this study, we investigated the impact of truncation and commonly-used tags addition into the CT region of human BST-2 on its intracellular trafficking and signaling as well as its anti-HIV-1 function. The CT-truncated BST-2 exhibited potent inhibition on Vpu-defective HIV-1 and even wild-type HIV-1. However, the N-terminal HA-tagged CT-truncated BST-2 retained little antiviral activity and dramatically differed from its original protein in the cell surface level and intracellular localization. Further, we showed that the replacement of the CT domain with a hydrophobic tag altered BST-2 function possibly by preventing its normal vesicular trafficking. Notably, we demonstrated that a positive charged motif “KRXK” in the conjunctive region between the cytotail and the transmembrane domain which is conserved in primate BST-2 is important for the protein trafficking and the antiviral function. These results suggest that although the CT of BST-2 is not essential for its antiviral activity, the composition of residues in this region may play important roles in its normal trafficking which subsequently affected its function. These observations provide additional implications for the structure-function model of BST-2.     

Trace detection of picloram using an electrochemical immunosensor based on three-dimensional gold nanoclusters

Picloram, a herbicide widely used for broadleaf weed control, is persistent and mobile in soil and water with adverse health and environmental effects. It is important to develop a sensitive method for accurate detection of trace picloram in the environment. In this article, a type of ordered three-dimensional (3D) gold (Au) nanoclusters obtained by two-step electrodeposition using the spatial obstruction/direction of the polycarbonate membrane is reported. Bovine serum albumin (BSA)-picloram was immobilized on the 3D Au nanoclusters by self-assembly, and then competitive immunoreaction with picloram antibody and target picloram was executed. The horseradish peroxidase (HRP)-labeled secondary antibody was applied for enzyme-amplified amperometric measurement. The electrodeposited Au nanoclusters built direct electrical contact and immobilization interface with protein molecules without postmodification and positioning. Under the optimal conditions, the linear range for picloram determination was 0.001-10 μg/ml with a correlation coefficient of 0.996. The detection and quantification limits were 5.0 × 10⁻⁴ and 0.0021 μg/ml, respectively. Picloram concentrations in peach and excess sludge supernatant extracts were tested by the proposed immunosensor, which exhibited good precision, sensitivity, selectivity, and storage stability.     

Which RhD alleles are risk factors stimulating allo- anti-D?

The aim of this study was to identify the specific RhD alleles that are risk factors for stimulating allo-anti-D and develop a precise strategy for blood transfusion. To confirm the D phenotype, red blood cells suspended in saline should react to serological anti-D from three manufacturers. An antibody screen test, a saline phase test and a micro-column test were conducted to identify allo-anti-D and other allo-antibodies. RhD alleles were genotyped by PCR using sequence-specific primers. Seven hundred subjects who were either pregnant or had undergone transfusion were enrolled in our study; however, 28 samples were excluded because their RhD alleles were normal, as revealed by tests using genotyping kits. A total of 498 cases (74.1%) were RhD-null (lacking exons 1–10 of RhD), 336 were DEL RhD 1227A (20.2%), and 38 were RHD-CE (2-9) -D (5.6%). There were 136 cases (20.2%) with allo-anti-D among the 672 cases, with an allo-anti-D prevalence of 126 cases (25.3%) in 498 cases that were RhD-null, followed by 10 cases (26.3%) among 38 cases with RHD-CE (2-9) -D, and none in 366 cases with RhD1227A. RhD genetic polymorphism was observed in RhD-negative individuals. We concluded that RhD-null and partial D are risk factors for alloimmunization to the D antigen and should be transfused with Rh-negative blood. RHD1227A recipients can be transfused with RhD-positive blood. Pregnant women with the d/d and D-CE(2-9)-D alleles require appropriate anti-D prophylaxis and RhD1227A may induce a higher tolerance.