Characterization of cymbidium mosaic virus coat protein gene and its expression in transgenic tobacco plants

Cymbidium mosaic virus (CyMV) is the most prevalent virus infecting orchids. Here, we report the isolation of partial cDNA clones encoding the genomic RNA of CyMV. Like most of the polyadenylated monopartite positive-strand RNA viruses, the open reading frame (ORF) coding for the viral coat protein (CP) is located at the 3 end. The ORF predicts a polypeptide chain of 220 amino acids with a molecular weight of 23 600. Sequence comparison of this ORF to the CP sequences of potato virus X(PVX) and white clover mosaic virus (WCIMV) revealed a strong amino acid homology in the mid-portion of the CP, but the overall homology was low. The CyMV CP gene was placed downstream of a cauliflower mosaic virus 35S promoter and the chimaeric gene was transferred into Nicotiana benthamiana. Transgenic plants expressing the CyMV CP were protected against CyMV infection.     

Redox control of iron regulatory proteins

Abstract

Increasing evidence suggests an important role of oxidant-induced damage in the progress of senescent changes, providing support for the free radical theory of aging proposed by Harman in 1956. However, considering that biological organisms continuously renew their structures, it is not clear why oxidative damage should accumulate with age. No strong evidence has been provided in favor of the concept of aging as an accumulation of synthetic errors (e.g. Orgels `error-catastrophe' theory and the somatic mutation theory). Rather, we believe that the process of aging may derive from imperfect clearance of oxidatively damaged, relatively indigestible material, the accumulation of which further hinders cellular catabolic and anabolic functions. From this perspective, it might be predicted that: (i) suppression of oxidative damage would enhance longevity; (ii) accumulation of incompletely digested material (e.g. lipofuscin pigment) would interfere with cellular functions and increase probability of death; (iii) rejuvenation during reproduction is mainly provided by dilution of undigested material associated with intensive growth of the developing organism; and (iv) age-related damage starts to accumulate substantially when development is complete, and mainly affects postmitotic cells and extracellular matrix, not proliferating cells. There is abundant support for all these predictions.     

An oral Salmonella vaccine promotes the down-regulation of cell surface Toll-like receptor 4 (TLR4) and TLR2 expression in mice

A single oral immunization with the Lon-protease-deficient Salmonella enterica serovar Typhimurium (strain CS2022) induced protective immunity in mice against a subcutaneous challenge with virulent Listeria monocytogenes as well as virulent Salmonella serovar Typhimurium. The populations of cell surface Toll-like receptor 4 (TLR4) and TLR2 on peritoneal macrophages decreased at week 6 after immunization. This population decrease was not reversed after a challenge with either Salmonella or Listeria. These results suggest that oral immunization with CS2022 induced immune tolerance correlated with the down-regulation of cell surface TLR expression. This down-regulation may in part account for the development of cross-protection against a Listeria challenge by immunization with CS2022.     

弧菌外膜蛋白OmpU的免疫交叉反应性和交叉保护性北大核心CSCD

【目的】通过对弧菌外膜蛋白Omp U的克隆、表达以及免疫学特性分析,明确外膜蛋白Omp U是否为弧菌的共同抗原,并具有免疫交叉反应性和交叉保护性。【方法】对弧菌外膜蛋白omp U基因进行克隆和生物信息学分析。分别制备副溶血弧菌、溶藻弧菌、创伤弧菌、拟态弧菌和霍乱弧菌的Omp U重组蛋白抗血清,对Omp U的免疫交叉反应特性以及抗原表位定位情况进行比较分析。以霍乱弧菌的Omp U重组蛋白免疫小鼠后,再以多种弧菌进行攻毒,分析其交叉免疫保护作用。【结果】外膜蛋白Omp U在弧菌种内和种间相似性分别为73.0%–100%和58.6%–89.0%,并至少存在9个保守的B细胞抗原表位。Omp U重组蛋白抗血清在弧菌种内和种间均产生显著的免疫交叉反应,识别弧菌中分子量35–40 k Da的同源蛋白。副溶血弧菌ATCC17802、创伤弧菌ATCC27562和拟态弧菌ATCC33653来源的Omp U重组蛋白抗体能识别供试菌株,提示这些菌株的Omp U抗原表位定位于细胞表面。Omp U重组蛋白对免疫后的小鼠具有交叉免疫保护作用,攻毒实验后小鼠相对存活率(RPS)为43.0%–100%。【结论】上述结果表明,外膜蛋白Omp U是弧菌中一种保守的共同抗原,具有免疫交叉保护性,可以作为弧菌广谱疫苗的候选抗原。     

交互保护对干酪乳杆菌ATCC 393~(TM)存活的影响

【目的】以干酪乳杆菌典型株ATCC 393TM(Lactobacillus casei ATCC 393TM)为实验菌株,研究其在多重胁迫环境下的交互保护应答机制。【方法】比较不同亚适应条件(热、H2O2、酸、胆盐)处理后菌体细胞在热致死条件(60℃)及氧致死条件H2O2(5mmol/L)下的存活率变化,并集中考察了最佳亚适应条件-酸适应的不同处理方式对细胞交互保护存活率、胞内pH以及脂肪酸含量的影响。【结果】交互保护对干酪乳杆菌ATCC393生理活性的影响因亚适应及致死条件而异:酸胁迫预适应能够显著提高细胞的交互胁迫抗性,其中,盐酸预适应的交互保护效果优于乳酸,其预适应引发的生理应答效应使细胞在应对热致死和氧致死胁迫时存活率分别提高了305倍和173倍;进一步的研究表明,酸预适应提高细胞存活率的作用机制可能与其能够显著改善胁迫环境下的胞内pH和细胞膜脂肪酸不饱和度相关。【结论】盐酸预适应对干酪乳杆菌典型株ATCC393的交互保护作用最为显著,并能够维持胁迫条件下细胞生理状态的相对稳定,本研究将有助于进一步解析干酪乳杆菌在对抗不同胁迫环境的过程中生理应答机制间的相互作用关系。     

禽多杀性巴氏杆菌粘附蛋白Cp39的交叉免疫保护作用

【目的】比较体内外增殖禽多杀性巴氏杆菌荚膜蛋白、天然粘附蛋白Cp39和重组粘附蛋白rCp39对小鼠的交叉保护作用。【方法】用NaCl提取法制备鸡胚尿囊液和DSA培养基增殖的C48-3株荚膜蛋白,并用电洗脱方法纯化Cp39蛋白,将rCp39蛋白以可溶形式表达在大肠杆菌BL21后,用Amylose Resin亲和层析柱纯化。分别以100μg剂量的鸡胚尿囊液增殖菌体荚膜蛋白、DSA培养基培养菌体荚膜蛋白、纯化的Cp39蛋白和rCp39蛋白通过皮下注射各试验组小鼠,生理盐水为对照组,第二次免疫后2周分别以A:1型菌C48-3株(6.7×102cfu)和A:3型菌C51-3株(1.1×103cfu)进行攻毒试验。采集免疫后小鼠血清,用ELISA法检测抗体水平,并计算免疫保护率,来评价4种抗原对小鼠的交叉保护效果。【结果】SDS-PAGE结果显示,体内外增殖禽多杀性巴氏杆菌荚膜蛋白的条带和分子量相似,且体内外表达的Cp39蛋白的分子量相同;ELISA结果表明Cp39免疫组小鼠和rCp39免疫组小鼠血清rCp39蛋白特异性抗体的水平显著高于其他两组(P0.05);保护试验表明,体外增殖菌体荚膜蛋白免疫组小鼠对同源C48-3株和异源C51-3株攻毒的保护率分别为100%和60%,鸡胚尿囊液增殖菌体荚膜蛋白免疫组小鼠、Cp39免疫组小鼠和rCp39免疫组小鼠对同源C48-3株和异源C51-3株攻毒的保护率分别为100%和80%。【结论】粘附蛋白Cp39是禽多杀性巴氏杆菌荚膜蛋白中的主要交叉保护抗原,可以作为禽霍乱亚单位疫苗。     

Accumulation of the compatible solutes, glycine-betaine and ectoine, in osmotic stress adaptation and heat shock cross-protection in the biocontrol agent Pantoea agglomerans CPA-2

AIMS: The effect of modifying the water activity (a(w)) of Pantoea agglomerans growth medium with the ionic solute NaCl on water stress resistance, heat-shock survival and intracellular accumulation of the compatible solutes glycine-betaine and ectoine were determined. METHODS AND RESULTS: The bacterium was cultured in an unmodified liquid medium or that modified with NaCl to 0.98 and 0.97 a(w), and viability of cells evaluated on a 0.96 a(w)-modified solid media to check water stress tolerance. Cells grown under ionic stress had better water stress tolerance than control cells. These cells also had cross-protection to heat stress (30 min, 45 degrees C). The modified cells accumulated substantial amounts of the compatible solutes glycine-betaine and ectoine in contrast to the control cells, which contained little or none of these two compounds. CONCLUSIONS: Improvement in osmotic and thermal tolerance of cells of the biocontrol agent P. agglomerans by modifying growth media with the ionic solute NaCl was achieved. The compatible solutes glycine-betaine and ectoine play a critical role in environmental stress tolerance improvement. SIGNIFICANCE AND IMPACT OF THE STUDY: This approach provides a method for improving the physiological quality of inocula and could have implications for formulation and shelf-life of biocontrol agents.     

Lactobacillus,Bifidobacterium and Lactococcus response to environmental stress: Mechanisms and application of cross-protection to improve resistance against freeze-drying

The review deals with lactic acid bacteria in characterizing the stress adaptation with cross-protection effects, mainly associated with Lactobacillus, Bifidobacterium and Lactococcus. It focuses on adaptation and cross-protection in Lactobacillus, Bifidobacterium and Lactococcus, including heat shocking, cold stress, acid stress, osmotic stress, starvation effect, etc. Web of Science, Google Scholar, Science Direct, and PubMed databases were used for the systematic search of literature up to the year 2020. The literature suggests that a lower survival rate during freeze-drying is linked to environmental stress. Protective pretreatment under various mild stresses can be applied to lactic acid bacteria which may enhance resistance in a strain-dependent manner. We investigate the mechanism of damage and adaptation under various stresses including heat, cold, acidic, osmotic, starvation, oxidative and bile stress. Adaptive mechanisms include synthesis of stress-induced proteins, adjusting the composition of cell membrane fatty acids, accumulating compatible substances, etc. Next, we reveal the cross-protective effect of specific stress on the other environmental stresses. Freeze-drying is discussed from three perspectives including the regulation of membrane, accumulation of compatible solutes and the production of chaperones and stress-responsive proteases. The resistance of lactic acid bacteria against technological stress can be enhanced via cross-protection, which improves industrial efficiency concerning the survival of probiotics. However, the adaptive responses and cross-protection are strain-dependent and should be optimized case by case.     

甲型流感病毒M2e通用疫苗的研究进展

流感严重地影响人们的身体健康和工作生活,给社会带来巨大经济损失。疫苗接种是预防流感的有效措施之一,市场上的流感疫苗包括流感灭活疫苗、减毒活疫苗和亚单位疫苗等。这些流感疫苗只能预防相同亚型流感病毒的感染,无法预防不同亚型流感病毒引起的季节性流感和流感大流行,因此迫切需要研发广谱的能预防不同亚型的甲型流感病毒感染的通用疫苗。在此简要介绍甲型流感病毒M2e通用疫苗的研究进展。     

Cross-protection between the metacestodes of Mesocestoides corti and Taenia crassiceps in mice

Novak M. 1984. Cross-protection between the metacestodes of Mesocestoides corti and Taenia crassiceps in mice. International Journal for Parasitology14: 497–501. Infection with M. corti generated significant resistance against a challenge with T. crassiceps introduced either 2 or 6 weeks after primary infection. Challenge infection with T. crassiceps did not influence primary infection with M. corti. Infection with T. crassiceps protected significantly against challenge with M. corti given 2 weeks but not 6 weeks after the primary infection. Challenge infection with M. corti significantly suppressed primary infection with T. crassiceps.