乙型肝炎病毒表面抗原-抗体复合物治疗慢性乙型肝炎患者病毒S基因变异研究

目的 研究应用乙型肝炎病毒表面抗原(HBsAg)-抗体复合物治疗性疫苗(YIC)治疗慢性乙型肝炎患者是否会诱生S基因免疫逃逸变异株的出现。方法 选取5例用30μg或60μgYIC治疗后血清乙型肝炎病毒(HBV)DNA水平下降>2log10、伴有乙型肝炎病毒e抗原(HBeAg)转阴应答,但在随访6个月后病毒DNA水平重复升高的患者作为研究对象,另选取1例对YIC治疗始终无应答患者和1例注射安慰剂患者作为对照,用聚合酶链反应(PCR)方法扩增治疗前(0周)及治疗后(44周)血清中HBV DNA的S基因、前-核心基因、核心基因启动子片段,并进行序列比对分析。结果 S基因“a”决定簇及前-核心基因均未发生变异,但YIC治疗后有3例HBV的核心基因启动子1762/1764位点序列有变异,另有2例在核心基因启动子的其他位点有核苷酸变异。结论 研究显示5例出现病毒重新复制的患者并非由于发生了病毒S基因逃逸变异所致。     

慢性乙型肝炎治疗中HBV YMDD变异的相关因素分析

目的 探讨拉米夫定治疗慢性乙型肝炎过程中HBV YMDD变异的相关因素。方法 对应用拉米夫定治疗的22例慢性乙型肝炎患者进行肝功能、乙肝病毒血清学标志物、HBV YMDD变异检测,同时进行肝组织病理学检查。结果 ALT异常率为55%,HBeAg血清转换率为13.6%,HBV YMDD变异发生率为31%,治疗前病毒量的高低不影响其治疗效果。5例患者肝穿组织中HBsAg和HBcAg依然阳性。结论 运用拉米夫定治疗慢性乙型肝炎6个月后可出现HBV YMDD变异,随着治疗时间延长,其变异发生率越高;HBeAg血清转换率不高;肝组织内仍处于炎症及纤维化状态。     

乙型肝炎病毒变异与肝细胞癌发生关系

乙型肝炎病毒（hepatitisBvirus,HBV）基因组复制时,以病毒前基因组RNA作为模板合成子代病毒DNA,催化该过程的逆转录酶缺乏校对功能,所以HBV易出现变异。近年来,各国学者通过比较肝细胞癌（hepatocellular carcinoma,HCC）患者和非HCC患者的HBV基因序列,发现HBV基本核心启动子区的A1762T／G1764A变异或T1753V变异、增强子Ⅰ区的G1053A或G1229A变异、前S蛋白的F141L变异、前s2区基因缺失变异和x基因的截短变异,分别是HCC的易患因素,而前c区常见的G1896A变异,与HCC的发生无关。增强子Ⅱ区的C1653T变异在c基因HBV感染中可能与发生HCC有关,而在A基因型可能无关。     

采用熔点曲线法研究乙肝病毒准种与拉米夫定临床耐药相关性

为了研究乙型肝炎病毒(HBV)准种与拉米夫定耐药的关系以指导临床用药,随机选取拉米夫定治疗后发生YMDD变异的慢性乙型肝炎(CHB)患者30例,以及停用拉米夫定后发生病毒反弹的CHB患者30例作为研究对象,同时以未经拉米夫定治疗的CHB患者30例为对照,采用聚合酶链反应(PCR)扩增这些病人体内HBV的P区,再用熔点曲线法分析3组患者体内的HBV准种情况。另外,采用相同方法对HBV C区、S区准种也进行了对比。结果显示,病毒变异组患者体内HBV P区准种数量为2.50±0.86个,病毒反弹组为5.30±0.95个,未治疗组为8.37±0.93个,3组间准种数量两两比较均有显著性差异(P<0.05)。HBV C区病毒变异组准种数量为6.10±1.86个,病毒反弹组为6.37±1.81个,未治疗组为6.33±1.64个,3组准种数量无显著性差异(P>0.05)。HBV S区病毒变异组准种数量为5.23±1.85个,病毒反弹组为6.17±1.93个,未治疗组为5.77±2.11个,3组准种数量无显著性差异(P>0.05)。HBV P区熔点曲线图显示,病毒变异组优势病毒群的熔点与病毒反弹组和未治疗组相比,已发生明显的偏移,而在HBV C区和S区熔点曲线图中,3组的波峰数和优势病毒群的熔点均没有明显变化。可见,在拉米夫定的作用下HBV P区准种数量减少,准种的性质也发生变化,发生变异后劣势耐药病毒株变为优势病毒株易被检测到。拉米夫定对HBV C区、S区作用不明显。     

新型冠状病毒序列变异时空分析系统的设计与实现

新型冠状病毒肺炎目前已进入全球大流行状态,多个国家出现疫情爆发。美国疾病管制局期刊《新兴传染病》发表的关于新型冠状病毒的最新研究结论显示,新型冠状病毒基本传染数R0的中位数高达5.7,这意味着在未来较长时间内新型冠状病毒可能会在人群中持续传播并发生变异。在这一背景下,如何监视病毒的变异,对于冠状病毒的研究和药物研发具有重要意义。本文基于来自GISAID的病毒基因组序列数据,设计和实现了新型冠状病毒变异时空分析系统。该系统可对来自不同国家和地区的新型冠状病毒序列数进行统计,对病毒序列在不同时间、不同空间内的变异情况进行分析和可视化,同时还支持不同序列之间的差异比对。该系统可为新型冠状病毒肺炎的研究和政府的疾病控制机构的决策提供支持。     

抗病毒药物的发展态势分析

<正>病毒是危害人体健康的主要病原体之一,至今被国际病毒分类委员会(ICTV)确认、对人类致病的病毒有千余种。病毒的基因组一旦发生变异,产生新的突变病毒株会对原有的药物产生抗药性,甚至引起局部或全球性的传染病蔓延,增加疾病防治的难度,抗病毒药物的开发则是应对的主要方法。截至2014年10月,全球各研究院所和医药企业至少已对5608种抗病毒药     

病毒性肝炎疫苗的研究进展

病毒性肝炎是由多种肝炎病毒感染肝细胞而引起的世界性常见传染病,传染性强,发病率高。病毒性肝炎分为甲型、乙型、丙型、丁型和戊型五种。由于病毒种类繁多,而且易发生变异,容易感染,治疗方案有限,常规治疗疗效不稳定且价格昂贵。因此,接种疫苗是目前较为有效的办法。本综述主要包括四个部分,即甲型、乙型、丙型和戊型病毒性肝炎的相应疫苗的介绍。     

人类最大的瘟疫——流感

流感是由正粘液病毒引起的下呼吸道传染病。流感病毒分为甲型、乙型和丙型。引起流感暴发流行的病毒主要是甲型流感病毒,乙型流感病毒可引起局部流行。流感起病急,剧烈头痛、发冷、发热、食欲减退、全身乏力、背部和四肢疼痛为主要症状。全身中毒症状很重,呼吸道炎症却很轻。严重病例发生下呼吸道并发症,如支气管炎、气管支气管炎和支气管肺炎。流感病毒传播快,新亚型出现,几个月内横扫全球。在流感大流行时,造成学校停课,工厂停工,机关瘫痪,军队失去战斗力,医院人满为患。在历史上,流感曾发生很多次世界性流行。近百年来,发生过四次很大规模的流行。甲型流感病毒的表面抗原经常发生变异,病毒变异又有抗原漂流(Antigenicdrift)和抗原突变(Antigenicshift)之分。抗原漂流为血凝素抗原结构微小变异,抗原突变为病毒在自然界进行基因重组。每当新亚型出现时,人群对新病毒缺乏免疫力,往往造成大流行。只有加强流感病毒生态学研究,弄清病毒变异的规律,人类才能制服流感。     

口服口服脊髓灰质炎疫苗国家引入IPV

背景 脊髓灰质炎及其控制脊髓灰质炎(脊灰)是脊灰病毒1、2和3型引起的一种急性传染病,经人→人接触(粪→口途径)传播,疫苗前时代,所有儿童均暴露于脊灰病毒,1／200的易感儿童暴露后发生麻痹型脊灰。     

急性传染病休克的临床诊治与转归分析

目的:探讨急性传染病休克患者的诊治策略,提高救治成功率.方法:回顾分析急性传染病休克患者的人口学、流行病学、病因分类、传染病发生至休克出现时间、早期临床诊治与转归等情况,总结诊治经验.结果:本组68例急性传染病休克主要来自呼吸道、消化道传染病,细菌和病毒是休克发生的主要病原,分别占54.4％和30.9％,仅25％的病例病前有明确的传染病接触史.51.9％的患者存在误诊误治现象.在明确休克发生病理机制的前提下,早期快速有效的抗休克、抗感染治疗,短期使用糖皮质激素,积极纠正酸碱、电解质紊乱,并给予必要的对症支持治疗,治愈出院率92.6％,平均康复住院时间3～11天,平均(5.8±2.4)天.结论:急性传染病休克早期误诊现象突出;给予积极抗体克、抗感染、激素治疗,纠正酸碱和电解质紊乱,结合对症支持治疗,可在短期内治愈患者.     

Construction of a replication-competent murine retrovirus vector expressing the human immunodeficiency virus type 1 tat transactivator protein.

A replication-competent Akv murine leukemia virus-based vector encoding the human immunodeficiency virus tat cDNA under control of the simian virus 40 early promoter sequences was constructed. The simian virus 40 tat sequences were placed within the U3 region of the 3' long terminal repeat. The resulting virus, derived by transfection, replicated efficiently in mouse NIH 3T3 cells and maintained the tat cDNA insert. It has been suggested that Tat function requires the presence of a human-specific cofactor, which is absent in murine cells. However, infection of murine cells with the Akv virus encoding tat resulted in significant transactivation of a human immunodeficiency virus long terminal repeat-driven reporter gene, indicating that human cofactors are not always required for Tat function. The vector system described may be useful for introduction of foreign genes in vivo and in whole animals when virus spread is required for efficient infection and levels of gene expression.     

Improved retroviral vectors for gene transfer and expression

We describe a set of murine retrovirus-based vectors that include unique cloning sites for insertion of cDNAs such that the cDNA can be driven by either the retroviral long terminal repeat, the immediate early promoter of human cytomegalovirus, or the simian virus 40 early promoter. The vectors carry the neomycin phosphotransferase gene expressed from an alternate promoter as a selectable marker. These vectors have been constructed to prevent viral protein synthesis from the remaining viral sequences, to yield high-titer virus stocks after introduction into retrovirus packaging cells, and to eliminate homologous overlap with viral DNAs present in retrovirus packaging cells in order to prevent helper virus production. Methods for generating high-titer virus are described.     

Adenovirus type 2 terminal protein: purification and comparison of tryptic peptides with known adenovirus-coded proteins.

The protein covalently bound to the 5' termini of adenovirus type 2 DNA has been purified from virus labeled with [35S]methionine, using exclusion chromatography of disrupted virions to isolate the DNA-protein complex, which is then digested with DNase. The terminal protein isolated from mature virus is most effectively labeled if the cells are exposed to [35S]methionine during the "intermediate" period of 13 to 21 h postinfection, suggesting that the protein is synthesized during this interval. The tryptic peptides of the terminal protein were compared with those of several known adenovirus-coded proteins and found to be unrelated. In particular, the terminal protein is not related to the 38-50K early proteins encoded by the leftmost 4.4% of the adenovirus genome, one region essential for the transforming activity of the virus. Neither is it related to the 72K single-strand-specific DNA binding protein, the minor virion component IVa2, or the major capsid component hexon.     

Amplification of Epstein-Barr virus (EBV) DNA by superinfection with a strain of EBV derived from nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) from a nasopharyngeal carcinoma (NPC) hybrid cell line (NPC-KT) lacking defective viral DNA molecules superinfected Raji cells and induced EBV early antigens (EA), as did virus from P3HR-1 cells, which contained defective molecules. The EBV polypeptides induced by NPC-KT appeared to be identical to those induced by P3HR-1 virus. The ability of NPC-KT virus to induce EA was enhanced more than 10-fold by treatment of superinfected cells with dimethyl sulfoxide; however, dimethyl sulfoxide treatment did not enhance superinfection by P3HR-1 virus. After infection, DNA synthesis of both the superinfecting NPC-KT virus and the resident Raji viral genome was induced. In addition to amplified Raji EBV episomal DNA, a fused terminal fragment of NPC-KT viral DNA was detected. The detection of fused terminal DNA fragments suggests that the superinfecting virion DNA either circularizes or polymerizes after superinfection and is possibly amplified through circular or concatenated replicative intermediates.     

Features of crossing-over in virus-infected tomato

The evidence of increased crossing over rate in tomato hybrids infected with TAV (Tomato aspermy virus), PVX (Potato virus X), TMV (Tobacco mosaic virus), TMV+PVX indicates the recombinogenic effect of viral infection. Cytological studies of the early diakinesis in healthy and virus-infected tomato revealed significant changes in chiasma number and position. The most significant changes were established for bivalents with two interstitial chiasmata and with one terminal and one interstitial. The data obtained indicate redistribution of the chiasmata position and induction of additional exchanges. The virus-induced recombination is segment-specific and depends on the host plant genotype, virus infection and the interaction between them.     

‘EARLY TERMINAL SEDATION’ IS A DISTINCT ENTITY

There has been much discussion regarding the acceptable use of sedation for palliation. A particularly contentious practice concerns deep, continuous sedation given to patients who are not imminently dying and given without provision of hydration or nutrition, with the end result that death is hastened. This has been called ‘early terminal sedation’. Early terminal sedation is a practice composed of two legally and ethically accepted treatment options. Under certain conditions, patients have the right to reject hydration and nutrition, even if these are life‐sustaining. Patients are also entitled to sedation as palliation for intolerable, intractable suffering. Though early terminal sedation is thought to be rare at present, the changing nature of palliative medicine suggests its use will increase. Arguments regarding early terminal sedation have failed to recognize early terminal sedation as a distinct legal and ethical entity. It can be seen as both the simple sum of treatment refusal and sedation for palliation, analogous to terminal sedation. It can also be seen as an indivisible palliative treatment, more analogous to assisted suicide or euthanasia. But ultimately, it is wholly analogous neither to terminal sedation given when death is imminent, nor to assisted suicide or euthanasia. This paper contends that early terminal sedation should be considered as a distinct entity. Such a reconception promises to provide a way forward in the debate, practice and policy regarding this contentious area of palliative medicine.     

The complete nucleotide sequence of the left very early region of Escherichia coli bacteriophage PRD1 coding for the terminal protein and the DNA polymerase

DNA molecules replicating in a linear form have been found in certain viruses and plasmids of both prokaryotic and eukaryotic origin. Characteristic of this type of molecules are the proteins covalently linked to their 5' ends and inverted terminal nucleotide sequences. The molecules replicate via a protein-priming mechanism, where participants include terminal protein and a specific polymerase. We report here the nucleotide sequence of the left very early region of Escherichia coli bacteriophage PRD1. This region codes for the terminal protein and the phage DNA polymerase. The predicted amino acid sequence of the terminal protein does not share homology with those of other known terminal proteins. The PRD1 DNA polymerase shows four regions of extensive homology to that of Bacillus subtilis phage phi 29. One of these conserved regions is also found in several animal virus DNA polymerases.     

Epstein-Barr virus episome-based promoter function in human myeloid cells.

Epstein-Barr virus (EBV) episomal replicons offer an expeditious means for amplifying transfected genes in human cells. A panel of EBV episomes was constructed to assess the relative utility of five distinct eukaryotic promoter elements for high level and inducible gene expression in stably transfected human myeloid leukemia cells. The Rous sarcoma virus 3' long terminal repeat (LTR) was most highly suited for EBV episome-based gene expression, whereas the lymphopapilloma virus and the SV40 early regulatory elements exhibited substantially lower activities. Chemically responsive promoter elements, such as the SV40 early, human metallothionein IIA and rat GRP78 gene promoters, retained their inducibility when EBV episome-based. Differences in gene expression obtained with the episomes reflected differential promoter activity rather than significant variations in episome copy numbers per cell. These observations provide guidelines for the optimal design of EBV episomal expression vectors for human expression work.