Structures of Foot-and-mouth Disease Virus with neutralizing antibodies derived from recovered natural host reveal a mechanism for cross-serotype neutralization

The development of a universal vaccine against foot-and-mouth disease virus (FMDV) is hindered by cross-serotype antigenic diversity and by a lack of knowledge regarding neutralization of the virus in natural hosts. In this study, we isolated serotype O-specific neutralizing antibodies (NAbs) (F145 and B77) from recovered natural bovine hosts by using the single B cell antibody isolation technique. We also identified a serotype O/A cross-reacting NAb (R50) and determined virus-NAb complex structures by cryo-electron microscopy at near-atomic resolution. F145 and B77 were shown to engage the capsid of FMDV-O near the icosahedral threefold axis, binding to the BC/HI-loop of VP2. In contrast, R50 engages the capsids of both FMDV-O and FMDV-A between the 2- and 5-fold axes and binds to the BC/EF/GH-loop of VP1 and to the GH-loop of VP3 from two adjacent protomers, revealing a previously unknown antigenic site. The cross-serotype neutralizing epitope recognized by R50 is highly conserved among serotype O/A. These findings help to elucidate FMDV neutralization by natural hosts and provide epitope information for the development of a universal vaccine for cross-serotype protection against FMDV.     

不同盐渍化生境野生乌拉尔甘草土壤细菌群落结构及功能预测分析

【目的】探究典型盐生药用植物野生乌拉尔甘草在不同盐渍化生境下土壤细菌群落多样性、组成和功能特征,有助于建立土壤盐分与甘草生长发育、药材品质形成相关的微生物组之间的联系,对栽培甘草药材品质提高具有重要意义。【方法】从野生乌拉尔甘草的6个主分布区采集原生境土壤,采用高通量测序技术比较非盐渍(un-salinization, US)、轻度盐渍(light salinization, LS)、中度盐渍(moderate salinization, MS)以及重度盐渍(heavy salinization, HS)生境中土壤细菌群落多样性、组成及功能的差异,并挖掘不同生境中优势细菌。【结果】野生乌拉尔甘草原生境土壤细菌群落丰富度和多样性在轻度盐渍(LS)组和中度盐渍(MS)组中明显高于非盐渍(US)组、重度盐渍(HS)组,且重度盐渍(HS)组最低。主成分分析(principal component analysis, PCA)表明不同盐渍程度组间的野生乌拉尔甘草土壤细菌群落组成和功能具有显著差异(P<0.05);冗余分析(redundancy analysis, RDA)表明,土壤盐分(total salt, TS)既是影响原生境土壤细菌群落组成也是影响群落功能的重要因子。属水平,非盐渍(US)组和轻度盐渍(LS)组中的显著优势细菌相同,均为植物有益菌,包括类诺卡氏菌属(Nocardioides)、链霉菌属(Streptomyces)、栖大理石菌属(Marmoricola);重度盐渍(MS)组中显著优势属既包括有益菌未鉴定_酸杆菌属(unidentified_Acidobacteria),也包括嗜盐菌盐单胞菌属(Halomonas)、海杆菌属(Marinobacter);重度盐渍(HS)组中显著优势细菌以嗜盐菌或耐盐菌为主,包括盐单胞菌属(Halomonas)、海杆菌属(Marinobacter)、楚帕氏菌属(Truepera)、别样矿生菌属(Aliifodinibius)、盐坑微菌属(Salinimicrobium)和需盐杆菌属(Salegentibacter)。PICRUSt功能预测分析强调非盐渍(US)组、轻度盐渍(LS)组和中度盐渍(MS)组中的土壤细菌群落与植物互作方面的潜力,表明非盐渍、轻度盐渍和中度盐渍生境中的有益菌对野生乌拉尔甘草生长发育、品质形成具有重要影响。PICRUSt功能预测同时也强调了重度盐渍(HS)组在自我修复适应高盐环境以及参与野生乌拉尔甘草耐盐性提高方面具有潜能,表明重度盐渍生境中的嗜盐菌和耐盐菌对乌拉尔甘草抗盐能力具有重要作用。中度盐渍生境兼具以上二者优势菌群的特征,是值得关注的类型。【结论】野生乌拉尔甘草土壤细菌群落多样性和丰富度在轻度盐渍和中度盐渍生境中明显高于非盐渍和重度盐渍生境;细菌群落的组成和功能在非盐渍和轻度盐渍生境中具有相似性,并与重度盐渍生境存在显著差异,中度盐渍生境兼具以上二者的特征。     

The biochemical and immunological characterization of two serpins from Clonorchis sinensis

Serpins (serine proteinase inhibitors) are evidenced to regulate numerous biological processes such as immunoregulation in parasitic helminths. The functions of serpins from Clonorchis sinensis remain unclear to date. In this study, two serpin genes, respectively denominated as CsproSERPIN and CsSERPIN2, had been selected from metacercaria cDNA library of C. sinensis. The biochemical activities of both recombinant proteins (rCsproSERPIN and rCsSERPIN2) were analyzed by assays of inhibition on some serine or cysteine proteases, the results showed that rCsproSERPIN significantly inhibited trypsin, chymotrypsin and thrombin, while rCsSERPIN2 inhibited only chymotrypsin. Moreover, cytokine and antibody measurements indicated that rats subcutaneously immunized with rCsproSERPIN and rCsSERPIN2 respectively developed a strong IFN-γ production and IgG2a levers of sera were higher than IgG1. Besides, immunoblot assays revealed that the rCsproSERPIN and rCsSERPIN2 could be recognized by the sera of rats infected with C. sinensis and the sera of rabbits immunized by excretory/secretory products. Furthermore, immunofluorescence assays illuminated the two were similarly localized in the reproductive organs such as vitelline glands, testis and eggs in adult stage. In short, all the results collectively indicated that CsproSERPIN and CsSERPIN2 might play important role in the parasite development by preventing the parasite from digestion by exogenous serine proteases, as well as CsproSERPIN and CsSERPIN2 probably involved in immunoregulation of host by inducing Th1-biased type cytokines in rats.     

Acaricidal properties of an Ailanthus altissima bark extract against Psoroptes cuniculi and Sarcoptes scabiei var. cuniculi in vitro

The potential acaricidal properties of an Ailanthus altissima bark extract were assessed against two common species of animal ectoparasitic mites, Psoroptes cuniculi and Sarcoptes scabiei var. cuniculi, in vitro. A. altissima bark extract was obtained by ethanol thermal circumfluence and tested at four concentrations (1.0, 0.5, 0.25 and 0.125 g/ml) on mites collected from rabbits. Compared to the fenvalerate treatment group, the A. altissima bark exhibited significant acaricidal properties for both mite species treated. The extract of concentrations of 1.0, 0.5 and 0.25 g/ml killed all tested S. scabiei within 7 h, however, only 1.0 and 0.5 g/ml of extract killed all treated P. cuniculi. The median lethal time (LT₅₀) values at 1, 0.5 and 0.25 g/ml were 0.60, 0.78, 1.48 h for S. scabiei and 0.74, 1.29, 3.33 h for P. cuniculi. The median lethal concentration (LC₅₀) for P. cuniculi was approximately 1.6 times that for S. scabiei var. cuniculi at 4 h. The extract showed stronger toxicity against S. scabiei than against P. cuniculi. Mortality rates increased with increasing concentration of extract administered and with increasing time post-treatment, indicating that the acaricidal activity of A. altissima bark extract is both time-dependent and dose-dependent. This is the first report on acaricidal activity of A. altissima against P. cuniculi and S. scabiei var. cuniculi. It indicates that A. altissima contain potential acaricidal compounds. Our study is the first step to develop potentially novel compounds from A. altissima for the effective control of mites in livestock.     

Treatment and prevention of natural heartworm (Dirofilaria immitis) infections in red pandas (Ailurus fulgens) with selamectin and ivermectin

Ten of the 48 red pandas in the Chengdu Research Base of Giant Panda Breeding, Sichuan province, China, died in 2006 after prolonged periods of depression, weight loss, and mucocutaneous membrane xanthochromia. During postmortem examination, live heartworms were found in the right cardiac ventricles and pulmonary arteries of all 10 animals. Selamectin and ivermectin were used for clinical prophylaxis in the remaining red pandas between December 2006 and November 2010. We observed a gradual decrease in morbidity and mortality during this period. As a consequence of our prophylaxis program, dirofilariosis did not occur in the remaining red pandas at Chengdu Research Base during 2010.     

An improved LC-MS/MS method for the quantification of prostaglandins E(2) and D(2) production in biological fluids

We report an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay that accurately measures prostaglandins D(2) (PGD(2)) and E(2) (PGE(2)) in cell culture supernatants and other biological fluids. The limit of detection for each prostaglandin was 20 pg/ml (0.20 pg, 0.55 fmol on-column), and the interday and intraday coefficients of variation were less than 5%. Both d(4)-PGE(2) and d(4)-PGD(2) were used as surrogate standards to control for differential loss and degradation of the analytes. Stability studies indicated that sample preparation time should be less than 8h to measure PGD(2) accurately, whereas preparation time did not affect PGE(2) measurement due to its greater stability in biological samples. As an application of the method, PGD(2) and PGE(2) were measured in culture supernatants from A549 cells and RAW 264.7 cells. The human lung alveolar cell line A549 was found to produce PGE(2) but no PGD(2), whereas the murine macrophage cell line RAW 264.7 produced PGD(2) and only trace amounts of PGE(2). This direct comparison showed that COX-2 gene expression can lead to differential production of PGD(2) and PGE(2) by epithelial cells and macrophages. Because PGE(2) is antiasthmatic and PGD(2) is proasthmatic, we speculate that the balance of production of these eicosanoids by epithelial cells and macrophages in the lung contributes to the pathogenesis of chronic obstructive pulmonary disease (COPD), bronchiectasis, asthma, and lung cancer.     

实时荧光定量PCR在猪繁殖与呼吸综合征病毒研究中的应用

猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)是一种严重危害种公猪和繁殖母猪及其仔猪的一种接触性传染病,是我国重要猪病病原体之一。建立一种快速、可靠的诊断方法,对于控制和消灭PRRSV至关重要。实时荧光定量PCR技术的发展为PRRSV在快速检测和鉴别诊断方面开辟了新思路。以下回顾了实时荧光定量PCR操作技术在PRRSV研究应用方面的研究进展,同时提出了该领域目前面临的问题,并对其未来发展方向进行了展望。     

The synthesis of N-doped carbon dots for visual differentiating and detection of tetracyclines

N-doped carbon dots (N-CDs) were synthesized from L -glutamine and triethanolamine using a one-step hydrothermal method. The N-CDs emitting blue fluorescence had selective responses to tetracyclines (TCs) and could be used as a fluorescent probe to realize the quantitative detection and qualitative analysis of TCs. A method for the determination of TCs using the N-CDs in actual samples was successfully established. The recovery rate was maintained at 97.50–105.60%, and the relative standard deviation (RSD) was less than 3%. In addition, TCs can be visually distinguished using filter paper by the different fluorescence colours (light green, dark blue, and yellow-green) of the N-CDs/TCs system under ultraviolet light. This study provides a relatively simple method to detect and identify TCs.