Impact of Bacillus thuringiensis toxin Cry1Ab on rumen epithelial cells (REC) – A new in vitro model for safety assessment of recombinant food compounds

The growing use of genetically modified crops necessitates viable screening methods for safety evaluation of recombinant feed, particularly for ruminants. A new sheep rumen epithelial cell culture is introduced as an in vitro cell system for safety evaluation especially focussing on feed and food compounds. We used lactate dehydrogenase (LDH) release, WST-1 conversion, ATP content and caspase 3/7 activity to evaluate cytotoxicity of Cry1Ab, one of the newly expressed Bt-proteins in transgene maize. The results were compared to the effects of valinomycin, a potassium ionophore known to induce cytotoxic effects on a wide range of cells. Whereas no toxicity of Cry1Ab was observed in short as well as in long term experiments, even at non-physiological high concentrations, exposure to valinomycin induced apoptosis and a significant response of all viability parameters after a number of hours. The ATP content and the WST-1 conversion reflecting the energy metabolism of the cells appear to be more sensitive indicators of valinomycin toxicity than the LDH release, a parameter which reflects the membrane integrity. This study presents an in vitro model system, that may be useful as a supplementary tool in toxicity screening before testing substances on animals in vivo.     

广州地区SARS流行期和非流行期献血人群SARS病毒抗体的流行病学调查

目的　分析广州地区SARS流行期和非流行期无偿献血人群中严重急性呼吸道综合征(SARS)病毒感染 情况,为制定预防输血传播SARS病毒措施提供科学依据。方法　采用酶联免疫吸附试验(ELISA)对无偿献血者血 液进行SARS病毒抗体筛查,对SARS病毒抗体阳性样本用荧光聚合酶链反应(PCR)法进一步检测SARS病毒核 酸。采用统一的个案调查表对20名SARS病毒抗体阳性无偿献血者进行电话咨询调查,同时对31名SARS康复献 浆者进行检测,分析相关数据作对照。结果　6120名无偿献血者中,共检测出SARS病毒抗体阳性56例,阳性率为 0.92%,31名SARS康复献浆者中,检测出SARS病毒抗体阳性30例,阳性率为96.77%;SARS流行期和非流行期 无偿献血者SARS病毒抗体阳性率分别为0.91%和0.92%,56名无偿献血者SARS病毒抗体阳性的平均S/CO值 (2.34)和抗体平均滴度(≤1∶2)均明显低于30名SARS康复献浆者的平均S/CO值(14.8)和抗体平均滴度(≤1∶ 32);56例SARS病毒抗体阳性无偿献血者血液样本均未检测出SARS病毒核酸;20例SARS病毒抗体阳性无偿献 血者的调查显示:献血者身体健康,无SARS患者密切接触史。结论　广州地区无偿献血人群中存在的低水平 SARS病毒抗体阳性率,是否表明SARS病毒抗体阳性献血者曾经感染过SARS病毒,尚需进一步     

Epitope selection and their placement for increased virus neutralization in a novel vaccination strategy for porcine epidemic diarrhea virus utilizing the Hepatitis B virus core antigen

Porcine epidemic diarrhea virus (PEDV) is a member of the Alphacoronaviridae genus within the Coronaviridae family. It is the causative agent of porcine epidemic diarrhea, a disease that can have mortality rates as high as 100% in suckling piglets. PEDV causes severe economic loss, and has been in existence for decades. A panzootic starting in 2010 renewed interest in the development of a universal vaccine toward PEDV. This report details several design changes made to a Hepatitis B virus core antigen (HBcAg)-based recombinant vaccine strategy, and their effect in vivo. Initially, several multi-antigen vaccine candidates were able to elicit antibodies specific to three out of four B-cell epitopes inserted into the chimeric proteins. However, a lack of virus neutralization led to a redesign of the vaccines. The focus of the newly redesigned vaccines was to elicit a strong immune response to the YSNIGVCK amino acid motif from PEDV. Genetically modified new vaccine candidates were able to elicit a strong antibody (Ab) response to the YSNIGVCK epitope, which correlated with an increased ability to neutralize the CO strain of PEDV. Additionally, the location of the inserted PEDV epitopes within the vector protein was shown to affect the immune recognition toward the native HBcAg during vaccination.     

Tissue-associated self-antigens containing exosomes: Role in allograft rejection

Exosomes are extracellular vesicles that express self-antigens (SAgs) and donor human leukocyte antigens. Tissue-specific exosomes can be detected in the circulation following lung, heart, kidney and islet cell transplantations. We collected serum samples from patients who had undergone lung (n?=?30), heart (n?=?8), or kidney (n?=?15) transplantations to isolate circulating exosomes. Exosome purity was analyzed by Western blot, using CD9 exosome-specific markers. Tissue-associated lung SAgs, collagen V (Col-V) and K-alpha 1 tubulin (Kα1T), heart SAgs, myosin and vimentin, and kidney SAgs, fibronectin and collagen IV (Col-IV), were identified using western blot. Lung transplant recipients diagnosed with bronchiolitis obliterans syndrome had exosomes with higher expression of Col-V (4.2-fold) and Kα1T (37.1-fold) than stable. Exosomes isolated from heart transplant recipients diagnosed with coronary artery vasculopathy had a 3.9-fold increase in myosin and a 4.7-fold increase in vimentin compared with stable. Further, Kidney transplant recipients diagnosed with transplant glomerulopathy had circulating exosomes with a 2-fold increased expression of fibronectin and 2.5-fold increase in Col-IV compared with stable. We conclude that circulating exosomes with tissue associated SAgs have the potential to be a noninvasive biomarker for allograft rejection.     

Immune checkpoint blockade opens an avenue of cancer immunotherapy with a potent clinical efficacy

Recent progress in tumor immunology has revealed that tumors generate immunologically restrained milieu during the process of their growth, which facilitates the escape of tumors from host immune systems. Immune checkpoint molecules, which transduce co‐inhibitory signals to immuno‐competent cells, are one of the most important components conferring the immunosuppressive capacity in the tumor microenvironment. Cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4) and programmed cell death‐1 (PD‐1) are typical immune checkpoint molecules intimately involved in the suppression of anti‐tumor immunity. Antibodies against those molecules have been developed, such as ipilimumab (anti‐CTLA‐4 antibody), nivolumab and pembrolizumab (anti‐PD‐1 antibody), and have been approved by regulatory agencies and used in some countries. Treatment with these antibodies demonstrates previously unobserved clinical efficacies superior to the conventional therapies. In this review, we first discuss the escape mechanisms of cancer from host immune systems, and then focus on the recent advances in immune checkpoint blockade therapy and on the new findings of related immune reactions, aiming to provide a better understanding of the novel cancer immunotherapies.     

RNAi suppression of rice endogenous storage proteins enhances the production of rice-based Botulinum neutrotoxin type A vaccine

Mucosal vaccines based on rice (MucoRice) offer a highly practical and cost-effective strategy for vaccinating large populations against mucosal infections. However, the limitation of low expression and yield of vaccine antigens with high molecular weight remains to be overcome. Here, we introduced RNAi technology to advance the MucoRice system by co-introducing antisense sequences specific for genes encoding endogenous rice storage proteins to minimize storage protein production and allow more space for the accumulation of vaccine antigen in rice seed. When we used RNAi suppression of a combination of major rice endogenous storage proteins, 13 kDa prolamin and glutelin A in a T-DNA vector, we could highly express a vaccine comprising the 45 kDa C-terminal half of the heavy chain of botulinum type A neurotoxin (BoHc), at an average of 100 μg per seed (MucoRice-BoHc). The MucoRice-Hc was water soluble, and was expressed in the cytoplasm but not in protein body I or II of rice seeds. Thus, our adaptation of the RNAi system improved the yield of a vaccine antigen with a high molecular weight. When the mucosal immunogenicity of the purified MucoRice-BoHc was examined, the vaccine induced protective immunity against a challenge with botulinum type A neurotoxin in mice. These findings demonstrate the efficiency and utility of the advanced MucoRice system as an innovative vaccine production system for generating highly immunogenic mucosal vaccines of high-molecular-weight antigens.     

间接ELISA检测HIV－1／－2抗体

报告了一种检测人类免疫缺陷病毒Ⅰ型和Ⅱ型（ＨＩＶ－１／－２）抗体的间接酶联免疫吸附测定（ＥＬＩＳＡ）方法。通过检测４ｌ份ＨＩＶ抗体参比血清（其中１３份为ＨＩＶ抗体阳性，２８份为ＨＩＶ抗体阴性），未见假阴性结果（０／１３）。在２８份阴性参比血清中，有２份呈假阳性。变异系数（ＣＶ）小于１５％。该结果符合参比血清说明书规定的标准。     

实验性重症肌无力动物模型的建立

从牛骨骼肌中提取乙酰胆碱受体（ＡｃｈＲ），经用１２５Ｉ标记α银环蛇神经毒素（α Ｂｇｔ）鉴定受体活性良好。用ＡｃｈＲ免疫Ｃ５７ＢＬ／６小鼠建立实验性自身免疫性重症肌无力（ＥＡＭＧ）模型。与对照组比较，小鼠在临床表现、肌电图衰减效应、血清中抗ＡｃｈＲ抗体和脾细胞对ＡｃｈＲ增殖反应检测中，均出现明显的阳性标志。ＥＡＭＧ动物模型的建立为进一步探索重症肌无力（ＭＧ）免疫发病机制和药物防治研究奠定基础     

The coating of erythrocytes with detergent-solubilized molecules: a general method for improved coupling of antigens and antibodies

A method is described by which different antigens and antibodies in solutions containing deoxycholate (DOC) may be coated to glutaraldehyde (GA)-fixed erythrocytes. This method, based on the use of CrCl3, yields erythrocytes which preserve the antigenicity and antibody activity of the coated molecules and can thus be applied to various assays in which indicator red cells are required. The sensitivity of the assays increases when these red cells are used. The cells form rosettes with the appropriate receptor positive cells. They sediment in Ficoll-Isopaque as do native erythrocytes and do not aggregate spontaneously even when coated at very high or low concentrations of CrCl3 or antigen. This coupling method, which is performed in the presence of DOC, and which requires only a small amount of antigen, is proposed for the coupling of cell membrane dissolved antigens.