Ultrasensitive Immunoassay Based on Anodic Near-Infrared Electrochemiluminescence from Dual-Stabilizer-Capped CdTe Nanocrystals

A sandwich-typed near-infrared (NIR) electrochemiluminescence (ECL) immunoassay was developed with dual-stabilizer-capped CdTe nanocrystals (NCs) as ECL labels and α fetoprotein antigen (AFP) as model protein. The dual-stabilizer-capped NIR CdTe NCs were promising ECL labels because of their NIR ECL emission of 800 nm, low anodic ECL potential of +0.85 V, and high biocompatibity, which can facilitate interference-free and highly sensitive ECL bioassays. Upon the immunorecognition of the immobilized AFP to its antibody labeled with dual-stabilizer-capped CdTe NCs, the proposed immunoassay displayed increasing ECL intensity, leading to a wide calibration range of 10.0 pg/mL to 80.0 ng/mL with a detection limit of 5.0 pg/mL [signal-to-noise ratio (S/N) = 3] without coupling any signal amplification procedures. The NIR ECL immunoassay for real samples displayed very similar results with those of Ru­(bpy)₃²⁺ reagent kit based commercial ECL immunoassay, which not only proved for the efficiency of NIR ECL from dual-stabilizer-capped CdTe NCs but also paved the road for development of novel ECL emitters and corresponding reagent kits

Enhancing Thermal Stability and Living Fashion in α‑Diimine–Nickel-Catalyzed (Co)polymerization of Ethylene and Polar Monomer by Increasing the Steric Bulk of Ligand Backbone

Development of thermally stable nickel-based catalysts is highly desirable for industrial gas-phase olefin polymerizations. On the basis of the strategy of promoting the thermostability of nickel catalyst by the ligand backbone, we herein reported novel dibenzobarrelene-derived α-diimine nickel precatalysts for ethylene polymerization. Increasing the steric bulk on the ligand backbone was expected to inhibit the <i>N</i>-aryl rotation of the α-diimine ligands by the repulsive interactions, thus enhancing thermal stability (100 °C) and living fashion a temperatures up to 80 °C. Bulk ligand backbone also improved tolerance of nickel catalyst toward polar groups, and the α-diimine nickel catalyst containing a 2,6-^<i>t</i>Bu-dibenzobarrelene backbone catalyzed living copolymerization of ethylene and methyl 10-undecenoate

Southernmost Asia Is the Source of Japanese Encephalitis Virus (Genotype 1) Diversity from which the Viruses Disperse and Evolve throughout Asia

<div><p>Background</p><p>Although a previous study predicted that Japanese encephalitis virus (JEV) originated in the Malaysia/Indonesia region, the virus is known to circulate mainly on the Asian continent. However, there are no reported systematic studies that adequately define how JEV then dispersed throughout Asia.</p><p>Methodology/Principal Findings</p><p>In order to understand the mode of JEV dispersal throughout the entire Asian continent and the factors that determine the dispersal characteristics of JEV, a phylogenetic analysis using Bayesian Markov chain Monte Carlo simulations was conducted on all available JEV E gene sequences in GenBank, plus strains recently isolated in China. Here we demonstrate for the first time that JEV lineages can be divided into four endemic cycles, comprising southern Asia, eastern coastal Asia, western Asia, and central Asia. The isolation places of the viruses in each endemic cycle were geographically independent regardless of years, vectors, and hosts of isolation. Following further analysis, we propose that the southernmost region (Thailand, Vietnam, and Yunnan Province, China) was the source of JEV transmission to the Asian continent following its emergence. Three independent transmission routes from the south to north appear to define subsequent dispersal of JEV. Analysis of JEV population dynamics further supports these concepts.</p><p>Conclusions/Significance</p><p>These results and their interpretation provide new insights into our understanding of JEV evolution and dispersal and highlight its potential for introduction into non-endemic areas.</p></div

Crystallization-Induced Redox-Active Nanoribbons of Organometallic Polymers

Polymer/inorganic functional nanostructures are essential for the fabrication of high-performance nanodevices in the future. The synthesis of hybrid nanostructures is hindered by complicated synthetic protocols or harsh conditions. Herein, we report a facile and scalable method for the synthesis of organometallic polymer nanoribbons through crystallization of polymers capped with a ferrate complex. Nanoribbons consisted of a single crystalline polymer lamella coated with a redox-active ferrate complex on both sides. The nanoribbons had a width of approximately 70 nm and a thickness of 10 nm. With the merit of highly ordered crystalline structures of polymers and functional coating layers, as well as a highly anisotropic nature, the nanoribbons are useful in nanodevices and biosensors

A Neuron-Specific Antiviral Mechanism Prevents Lethal Flaviviral Infection of Mosquitoes

<div><p>Mosquitoes are natural vectors for many etiologic agents of human viral diseases. Mosquito-borne flaviviruses can persistently infect the mosquito central nervous system without causing dramatic pathology or influencing the mosquito behavior and lifespan. The mechanism by which the mosquito nervous system resists flaviviral infection is still largely unknown. Here we report that an <i>Aedes aegypti</i> homologue of the neural factor <i>Hikaru genki</i> (<i>AaHig</i>) efficiently restricts flavivirus infection of the central nervous system. <i>AaHig</i> was predominantly expressed in the mosquito nervous system and localized to the plasma membrane of neural cells. Functional blockade of AaHig enhanced Dengue virus (DENV) and Japanese encephalitis virus (JEV), but not Sindbis virus (SINV), replication in mosquito heads and consequently caused neural apoptosis and a dramatic reduction in the mosquito lifespan. Consistently, delivery of recombinant AaHig to mosquitoes reduced viral infection. Furthermore, the membrane-localized AaHig directly interfaced with a highly conserved motif in the surface envelope proteins of DENV and JEV, and consequently interrupted endocytic viral entry into mosquito cells. Loss of either plasma membrane targeting or virion-binding ability rendered AaHig nonfunctional. Interestingly, <i>Culex pipien pallens</i> Hig also demonstrated a prominent anti-flavivirus activity, suggesting a functionally conserved function for Hig. Our results demonstrate that an evolutionarily conserved antiviral mechanism prevents lethal flaviviral infection of the central nervous system in mosquitoes, and thus may facilitate flaviviral transmission in nature.</p></div

The spatiotemporal migration of Genotype 1 JEV since the 1970s.

<p>The different panels represent temporal projections of reconstructed migration events in last 40 years (1970, 1978, 1981, 1990, 2000, 2003, 2006 and 2010, respectively). The different colors, yellow, green, light blue, blue, dark blue, purple, orange, red, dark red demonstrates for 1970, 1978, 1981, 1990, 2000, 2003, 2006 and 2010, respectively. The panels only show the tendency of migration events or partial migration events that have occurred up to a particular date, assuming that the virus migrates at a constant rate over the inferred time span of the branch. Blue circles mark the hot point of migration events. AF, Afghanistan; PK, Pakistan; IN, India; NP, Nepal; BT, Bhutan; BG, Bangladesh; BM, Burma; TH, Thailand; LA, Laos; VN, Vietnam; KH, Cambodia; MY, Malaysia; ID, Indonesia; PP, Papua New Guinea; AU, Australia; KP, North Korea; KR, South Korea; JP, Japan. Chinese provinces: HLJ, Heilongjiang Province; JL, Jilin Province; LN, Liaoning Province; NM, Neimenggu; XJ, Xinjiang; BJ, Beijing, TJ, Tianjin; HeB, Hebei Province; SX, Shanxi Province; SaX, Shaanxi Province; GS, Gansu Province; QH, Qinghai Province; NX, Ningxia; SD, Shandong Province; SH, Shanghai; JS, Jiangsu Province; AH, Anhui Province; HeN, Henan Province; XZ, Xizang; ZJ, Zhejiang Province; JX, Jiangxi Province; HuB, Hubei Province; CQ, Chongqing; SC, Sichuan Province; HuN, Hunan Province; GZ, Guizhou Province; YN, Yunnan Province; FJ, Fujian Province; GD, Guangdong Province; GX, Guangxi; HN, Hainan; TW, Taiwan; MG, Mongolia.</p

The antiviral effect of <i>Hig</i> in JEV infection of <i>C</i>. <i>pipiens pallens</i>.

<p>(A-C) Inoculation of <i>Culex pipiens pallens Hig</i> (<i>CpHig</i>) dsRNA significantly decreased the <i>CpHig</i> expression in the whole mosquitoes and heads of <i>C</i>. <i>pipiens pallens</i> at both the mRNA (A and B) and protein (C) levels. The <i>CpHig</i> abundance was assessed by SYBR Green qPCR (A and B) and immuno-blotting with an AaHig antibody (C) at 6 days post dsRNA microinjection. (D-G) Silencing <i>CpHig</i> enhanced JEV infection in <i>C</i>. <i>pipiens pallens</i>. 10 M.I.D.₅₀ JEV were inoculated at 3 days post <i>CpHig</i> dsRNA inoculation. The viral load of whole bodies (D and E) and heads (F and G) was assessed at 3 days and 6 days post-infection via Taqman qPCR and normalized with <i>Culex actin</i>. (H-K) Immuno-blockade of CpHig enhanced the JEV replication in <i>C</i>. <i>pipiens pallens</i>. The murine AaHig antibody, crossreacting with CpHig, was premixed with 10 M.I.D.₅₀ JEV to co-inoculate into the <i>Culex</i> mosquitoes thorax. The treated mosquitoes were sacrificed to examine the viral load in the mosquito bodies (H and J) and heads (I and K) at 3 and 6 days post-infection by TaqMan qPCR and normalized against <i>Culex actin</i>. (D-K) The primers and probes of Taqman qPCR were described in the <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004848#ppat.1004848.s022" target="_blank">S1 Table</a>. The experiments were repeated 3 times with similar results. One dot represents 1 mosquito and the horizontal line represents the median of the results. The data were statistically analyzed by the non-parametric <i>Mann-Whitney</i> test.</p

The role of <i>AaHig</i> in flaviviruses infection of <i>A</i>. <i>aegypti</i>.

<p>Immuno-blockade of AaHig enhanced the DENV-2 (A-B) and JEV (C-D) infections in the whole bodies (i) and heads (ii) of mosquitoes. The murine AaHig antibody, in the 10-fold serial dilutions, was premixed with 10 M.I.D.₅₀ viruses to co-microinject into the thorax of mosquitoes. The treated mosquitoes were sacrificed to examine the viral load in the whole mosquito bodies (i) and heads (ii) at 3 (A, C) and 6 (B, D) days post-infection by TaqMan qPCR and normalized against <i>A</i>. <i>aegypti actin</i>. The results were reproduced by 3 times. One dot represents 1 mosquito/head and the horizontal line represents the median of the results. The data were analyzed statistically using the non-parametric <i>Mann-Whitney</i> test.</p

Maximum clade credibility tree for E gene sequences of genotype 1 JEV.

<p>Seven clusters were identified and estimated TMRCAs of these clusters (with their 95% HPD values in parentheses) are shown. Four endemic cycles were grouped based on the geographical locations of JEV strains in each cluster. Red, blue, olive and turquoise were used to mark strains from southernmost Asia, eastern coastal Asia, western Asia, and central Asia, respectively. Posterior probability values of each cluster and endemic cycles were showed in the right of the nodes. In order to present all available sequences in the tree, black triangles were used to condense strains with the same isolation place and similar isolation times.</p

Bayesian skyline plots for genotype 1 JEV.

<p>Highlighted areas correspond to 95% HPD intervals.</p