In-silico characterization and RNA-binding protein based polyclonal antibodies production for detection of citrus tristeza virus

Citrus tristeza virus (CTV) is the etiologic agent of the destructive Tristeza disease, a massive impediment for the healthy citrus industry worldwide. Routine indexing of CTV is an essential component for disease surveys and citrus budwood certification for production of disease-free planting material. Therefore, the present study was carried out to develop an efficient serological assay for CTV detection based on the RNA binding protein (CTV-p23), which is translated from a subgenomic RNA (sgRNA) that accumulates at higher levels in CTV-infected plants. CTV-p23 gene was amplified, cloned and polyclonal antibodies were raised against recombinant CTV-p23 protein. The efficacy of the produced polyclonal antibodies was tested by Western blots and ELISA to develop a quick, sensitive and economically affordable CTV detection tool and was used for indexing of large number of plant samples. The evaluation results indicated that the developed CTV-p23 antibodies had an excellent diagnostic agreement with RT-PCR and would be effective for the detection of CTV in field samples. Furthermore, CTV-p23 gene specific primers designed in the present study were found 1000 times more sensitive than the reported coat protein (CTV-p25) gene specific primers for routine CTV diagnosis. In silico characterizations of CTV-p23 protein revealed the presence of key conserved amino acid residues that involved in the regulation of protein stability, suppressor activity and protein expression levels. This would provide precious ground information towards understanding the viral pathogenecity and protein level accumulation for early diagnosis of virus.     

环状RNA在恶性肿瘤发生发展和诊疗中的研究进展

环状RNA(circRNA)是一类共价闭合环状的内源性非编RNA,在各种真核细胞基因组广泛存在。因其具有丰度高、结构稳定、高度保守及组织特异表达等性质,成为最近几年研究的热点。研究发现,circRNA竞争性吸附微小RNA(miRNA),作为miRNA海绵,参与多种基因的表达调控,在肿瘤发生发展、侵袭转移等过程中发挥重要作用。该文就circRNA的起源、特征、功能及其在肿瘤发生发展、侵袭转移、诊断预后方面的研究作以下综述。     

沉默囊性纤维化跨膜传导调节因子对大鼠海马神经元细胞线粒体功能及氧化应激的影响

目的探讨沉默囊性纤维化跨膜传导调节因子(cystic fibrosis transmembrane conductance regulator,CFTR)在大鼠海马神经元细胞线粒体功能及氧化应激中的作用。方法18只SD大鼠随机分为CFTR小干扰RNA(small interfering RNA,siRNA)组、阴性对照组、空白对照组各6只。分离3组海马神经元细胞,取对数生长期细胞进行实验。CFTR siRNA组神经元细胞转染CFTR siRNA,阴性对照组转染阴性对照siRNA,空白对照组不转染。转染后培养48 h,采用Western blot法检测3组神经元细胞线粒体CFTR蛋白相对表达量,JC-1荧光探针检测线粒体膜电位,荧光分光光度法检测线粒体活性氧(reactive oxygen species,ROS)和过氧化氢(hydrogen peroxide,H2O2)表达,氧电极法测定线粒体呼吸控制率(respiratory control rate,RCR),荧光素酶发光法检测线粒体三磷酸腺苷(adenosine triphosphate,ATP)浓度,高效液相色谱法检测线粒体谷胱甘肽(glutathione,GSH)和氧化型谷胱甘肽(oxidized glutathione,GSSG)表达。结果转染后培养48 h,CFTR siRNA组神经元细胞线粒体CFTR蛋白相对表达量(0.09±0.01)、线粒体膜电位[(247.16±34.28)mV]、ATP[(11.71±2.54)mol/g]、RCR(4.69±0.82)、GSH[(0.71±0.12)nmol/μg]、GSH/GSSG值(0.31±0.08)低于空白对照组[0.42±0.07、(432.18±56.04)mV、(24.18±3.64)mol/g、7.94±1.21、(1.62±0.23)nmol/μg、1.65±0.27]和阴性对照组[0.38±0.06、(434.07±52.13)mV、(22.97±3.43)mol/g、7.83±1.18、(1.57±0.21)nmol/μg、1.63±0.24](P<0.05),线粒体H2O2水平(1.73±0.11)高于空白对照组(1.00±0.02)和阴性对照组(1.08±0.06)(P<0.05);空白对照组神经元细胞线粒体CFTR蛋白相对表达量及线粒体膜电位、ATP、RCR、H2O2、GSH、GSH/GSSG值与阴性对照组比较差异均无统计学意义(P>0.05)。结论沉默大鼠神经元细胞线粒体CFTR可引起海马神经元细胞线粒体功能障碍,增强氧化应激反应。     

Detection and clinical features of hepatitis C virus type 6 infections in blood donors from Hong Kong

The genotype distribution of hepatitis C virus (HCV) was investigated in 212 viraemic blood donors from Hong Kong. A subset of the samples was investigated using three different genotyping assays to establish the accuracy of each in this population. These assays were restriction fragment length polymorphism (RFLP) of amplified 5′ noncoding region (5′NCR) sequences, RFLP of the core region, and a serotyping assay using peptides from two antigenic regions of NS4. Genotypes detected in Hong Kong blood donors were 1a (6.2%), 1b (58.8%), 2a (1.4%), 2b (1.4%), 3a (1.9%), and 6a (27.0%). All genotyping assays produced concordant results. No evidence was obtained for the presence of type 6 group variants recently identified in Southeast Asia, other than type 6a. A serotyping assay based upon the detection of type-specific antibody to epitopes in NS4 produced similar results to the genotyping assays (98% concordance), but a reduced sensitivity (75%) compared with genotyping methods. Sequence variation in NS4 was not the cause of the reduced rate of detection of type 6 antibody in this population. Eighty-four percent donors infected with type 6a were male, compared to 75% donors infected with type 1b. The median alanine transaminase (ALT) level in type 6 infected donors was lower than in type 1b, (43.8 and 51.1 U/l, respectively) although these values were not statistically significant (P = 0.094). There was no significant difference between the ages of donors infected with types 1b and 6a. Risk factors for HCV infection in the blood donors included blood transfusion, intravenous drug abuse, and tattooing. A significantly greater number of donors infected with HCV-6a reported a history of drug abuse (66%) than donors infected with HCV-1b (7%). © 1996 Wiley-Liss, Inc.     

Sequence and genomic organization of GBV-C: A novel member of the flaviviridae associated with human non-A-E hepatitis

Recently, sequences from a novel virus, termed GB virus C (GBV-C), were identified in serum from several patients with cryptogenic hepatitis. In the present study, the nucleotide sequence of this virus has been extended to near-genome length. GBV-C encodes a putative single large polyprotein in which the structural proteins are positioned at the N-terminal end, with the nonstructural proteins located at the C-terminal end. Amino acid sequence analysis of this large polyprotein reveals the presence of protease, helicase, and replicase motifs. Sequence alignments of the polyprotein followed by phylogenetic analyses suggest that GBV-C is a member of the Flaviviridae, most closely related to the recently described GB virus A. © 1996 Wiley-Liss, Inc.     

Absence of extensive genetic heterogeneity of hepatitis C virus in antibody-negative chronic hepatitis C

Hepatitis C virus (HCV) carriers usually have antibodies to HCV; however, there are viremic individuals without these antibodies. To investigate whether variations of the viral genome are responsible for this discrepancy, the nucleotide and deduced amino acid sequences of HCV capsid and nonstructural regions obtained from 15 viremic patients were examined. These 15 patients were infected with type 1b HCV, and 10 did not have antibody to HCV assayed with second-generation tests. The nucleotide homology of the 5 seropositive and 10 seronegative patients with the HCV prototype sequence were 91.6% and 91.9%, respectively, in the capsid region. There was no apparent difference in the deduced amino acid sequences between the two groups of patients studied (94% vs. 95%). The nucleotide and amino acid sequences of a part of the nonstructural region 3 also showed similar results. These findings suggest that absence of antibodies against both capsid and nonstructural peptides in HCV carriers is not caused by genetic heterogeneity of the viral epitopes. © 1996 Wiley-Liss, Inc.