Regulation of influenza virus infection by microRNAs

MicroRNAs(miRNAs) are small noncoding RNAs of 18–25 nucleotides(nt) in length that represent key regulators of many normal cellular functions through the inhibition of mRNA translation and mRNA degradation. To date, over 2 500 mature miRNAs have been identified in plants, animals and several types of viruses. Influenza A virus(IAV), which is a negativesense, single-stranded RNA virus, does not encode viral miRNA. However, IAV infection can alter the expression of host miRNAs, either in cell culture or in host. In turn, host miRNAs regulate IAV life cycle through directly binding to IAV genome or indirectly targeting host factors associated with viral replication. In this review, we briefly summarized the role and significance of miRNA in relation to IAV pathogenesis. Understanding the role of cellular miRNAs during viral infection may be beneficial to the identification of novel therapeutic strategies to block IAV replication.     

Identification of virus-encoded microRNAs

RNA silencing processes are guided by small RNAs that are derived from double-stranded RNA. To probe for function of RNA silencing during infection of human cells by a DNA virus, we recorded the small RNA profile of cells infected by Epstein-Barr virus (EBV). We show that EBV expresses several microRNA (miRNA) genes. Given that miRNAs function in RNA silencing pathways either by targeting messenger RNAs for degradation or by repressing translation, we identified viral regulators of host and/or viral gene expression.     

小RNA病毒致病机理的研究

很多小RNA科病毒感染宿主细胞后可通过自身的核酸序列或病毒性蛋白产物控制靶细胞的生命活动,而被感染细胞也会通过自身的调控机制对侵染的病毒进行有限的反击,这种现象被认为是宿主细胞对抗小RNA科病毒侵染的防御机制.这种侵染与抵抗的互作机制可由某些病毒蛋白对细胞产生信号干扰或细胞自身翻译合成的细胞因子对病毒的复制路径进行封堵来实现.虽然这些信号通路的上游事件是不同的,但最后的效应却很统一,即使细胞崩解或者细胞将自身按照一定程序与所侵入的病毒同归于尽.此外,一些病毒蛋白具有抑制细胞程序性自杀的功能,它们能够令感染病毒后的细胞不死亡,形成病毒与宿主细胞共存的持续性感染状态.     

石斑鱼虹彩病毒SGIV感染致病的细胞分子基础及免疫防控对策

虹彩病毒(Iridovirus)是目前海水和淡水养殖鱼类最严重的病毒性病原之一,已从100多种鱼类中分离鉴定出该病毒。石斑鱼虹彩病毒(Singapore grouper iridovirus,SGIV)是从新加坡养殖的患病石斑鱼中分离鉴定的高致病性虹彩病毒,是虹彩病毒科Iridoviridae蛙病毒属Iridovirus 1种新的病毒。本文从以下几个方面对SGIV的研究进行综述:SGIV的形态、超微结构及其在石斑鱼细胞中的复制和装配过程;SGIV病毒基因组、转录组、囊膜蛋白质组及miRNAs的解析;SGIV感染宿主靶标组织的鉴定;病毒侵染的入侵方式、运动轨迹和胞内运输的实时追踪;SGIV感染宿主引起类凋亡的死亡机制及介导的信号通路的揭示;多种宿主免疫抗病基因对病毒感染的调节作用;多种SGIV的检测技术,包括基于抗体的流式细胞技术、微流控芯片检测技术、环介导等温扩增技术及核酸适配体检测方法等;SGIV的灭活疫苗、亚单位疫苗和DNA疫苗的研制等。以期为深入阐明SGIV感染致病机理奠定坚实的理论基础,为发展抗病毒对策提供技术支撑。     

猪长链非编码RNA lnc-000649在PRRSV感染增殖中的作用

长链非编码RNA(lncRNA)在免疫及病毒与宿主互作中发挥重要作用.本研究在猪PAM细胞中发现一种新的猪长链非编码RNA tnc-000649,其全序列长1 483 bp.利用荧光定量PCR技术检测了猪繁殖与呼吸综合征病毒(PRRSV)感染前后PAM细胞中lnc-000649的表达水平,发现其在PRRSV感染后表达显...     

M蛋白基因shRNA抑制PRRSV在Marc145细胞中复制的研究

 【目的】通过靶向PRRSV基因组中的M基因的siRNA来抑制PRRSV在Marc145细胞中的复制。【方法】构建4个能转录小发夹RNA（shRNA）的质粒,将其与靶蛋白表达质粒共转染HEK293A细胞,观察荧光或进行半定量PCR;或将其转染Marc145细胞,感染PRRSV后进行IFA、TCID50和实时PCR检测。【结果】shRNA表达质粒对M融合蛋白表达的抑制率约为50％,使M真核质粒表达蛋白的mRNA水平降低54%～64%,表达的shRNA在PRRSV感染后48 h使病毒的TCID50和mRNA水平均降低到1/10～1/100倍,间接免疫荧光结果表明shRNA表达质粒转染孔的荧光细胞数显著减少。【结论】shRNA表达质粒特异性的抑制了靶蛋白M和PRRSV的复制,靶向PRRSV基因组M基因不同区域的siRNA可以作为控制该病毒传播的候选策略。     

Pig macrophages with site-specific edited CD163 decrease the susceptibility to infection with porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome (PRRS) is recognized as one of the most infectious viral diseases of swine. Although Cluster of differentiation 163 (CD163) is identified as an essential receptor for mediating PRRS virus (PRRSV) infection, the important residues involved in infection on CD163 are still unclear. Therefore, it is very important to identify these key residues to study the mechanism of PRRSV infection and to generate anti-PRRSV pigs. In this study, we first generated immortalized porcine alveolar macrophage (IPAM) cell lines harboring 40-residues (residues 523–562, including R561 (arginine (R) at position 561)) deletion of CD163. PRRSV infection experiments showed that these IPAM cell lines were completely resistant to PRRSV infection. We then generated cloned pigs carrying CD163-R561A (an arginine (R) to alanine (A) substitution at position 561 of CD163). PRRSV challenge experiments in porcine alveolar macrophages (PAMs) isolated from the CD163-R561A pigs showed significantly lower susceptibility to PRRSV than that of CD163-R561 PAMs. Through this study, we show that CD163 523–562 contains essential residues for mediating PRRSV infection, and that CD163 R561 significantly contributes to PRRSV infection but is not essential for infection. These functional sites can therefore serve as new targets for understanding the mechanism of PRRSV infection. Furthermore, CD163-R561A pigs can be used as an important model for improving pig germplasm with resistance against PRRSV.     

植物转基因抗性策略研究进展

通过转基因技术使植物获得抗病性是控制植物病毒感染的一种重要技术途径。RNA干扰技术的出现为植物转基因抗性策略的研究提供了新思路。植物转基因抗性产生方法主要是通过表达不同的病毒蛋白(外壳蛋白、复制蛋白、运动蛋白及其他病毒蛋白)、RNAs(反义RNA、卫星RNA、缺陷干扰RNA、发夹RNA及人工微小RNA)、非病毒基因(核酸酶、抗病毒蛋白抑制子及植物体)、宿主来源的抗性基因(显性抗性基因和隐性抗性基因)及各种宿主防御反应因子等。介绍了以上几种抗性策略并分析了目前尚存在的问题,以期为植物转基因抗性策略研究的学者提供参考。     

Critical role of cytochrome c1 and its cleavage in porcine reproductive and respiratory syndrome virus nonstructural protein 4-induced cell apoptosis via interaction with nsp4

Porcine reproductive and respiratory syndrome virus(PRRSV) actively induces cell apoptosis both in vitro and in vivo,which can contribute critically to viral pathogenesis.Previous studies have shown that the PRRSV nonstructural protein 4(nsp4) is an important mediator of this process,but the underlying molecular details remain poorly understood.In this study,we found that the PRRSV nsp4 interacted with the mitochondrial inner membrane protein cytochrome c1(cyto.c1) and induced its proteolytic cleavage.Interestingly,the cleaved N-terminal fragment of cyto.c1 was found to exert apoptotic activity,which could cause mitochondrial fragmentation,resulting in apoptotic cell death.And RNA interference(RNAi) silencing experiments further confirmed the crucial role which cyto.c1 played in nsp4-and PRRSV-induced cell apoptosis.Thus,our data provide an important piece of mechanistic clues for PRRSV-induced cell apoptosis and also elucidate a novel mechanism for the 3 C-like proteases in this finding.     

Complex I binding by a virally encoded RNA regulates mitochondria-induced cell death

Human cytomegalovirus infection perturbs multiple cellular processes that could promote the release of proapoptotic stimuli. Consequently, it encodes mechanisms to prevent cell death during infection. Using rotenone, a potent inhibitor of the mitochondrial enzyme complex I (reduced nicotinamide adenine dinucleotide-ubiquinone oxido-reductase), we found that human cytomegalovirus infection protected cells from rotenone-induced apoptosis, a protection mediated by a 2.7-kilobase virally encoded RNA (beta2.7). During infection, beta2.7 RNA interacted with complex I and prevented the relocalization of the essential subunit genes associated with retinoid/interferon-induced mortality-19, in response to apoptotic stimuli. This interaction, which is important for stabilizing the mitochondrial membrane potential, resulted in continued adenosine triphosphate production, which is critical for the successful completion of the virus' life cycle. Complex I targeting by a viral RNA represents a refined strategy to modulate the metabolic viability of the infected host cell.     

高致病性猪繁殖与呼吸综合征病毒样品对细胞的敏感性

从疑似猪繁殖与呼吸综合征病毒(PRRSV)的发病猪场采集组织和血清样品并按病料分成2组,通过反转录—聚合酶链反应(RT-PCR)方法检测样品中高致病性PRRSV发生变异的Nsp2部分基因,初步筛选出PRRSV阳性样品后分别通过Marc-145和PAM细胞分离培养。结果表明：从45份阳性病料中成功分离到29份高致病性PRRSV,其中从血清样品中成功分离的约占总数72.5%,从组织样品中成功分离的约占总数27.5%;通过Marc-145细胞分离获得的病毒有19份,通过PAM细胞分离获得的有24份,其中有14份是Marc-145和PAM共同分离得到。试验获得的血清是高致病PRRSV分离的理想样品,该病毒对Marc-145和PAM细胞的敏感性差异不显著。     

猪繁殖与呼吸综合征·猪瘟和猪圆环病毒Ⅱ型混合感染的鉴定及病原特性分析

[目的]鉴定由猪瘟病毒（CSFV）、猪繁殖与呼吸综合征病毒（PRRSV）、猪圆环病毒Ⅱ型（PCV2）引发的猪疫病并进行病原特性分析。[方法]采集湖南湘潭（编号为HN/XT）发病猪的组织和脏器,进行DNA、RNA提取,然后进行PCR扩增、测序;同时采用细胞分离技术进行毒株的分离、鉴定。[结果]测序分析结果表明,CSFV、PRRSV和PCV2与目前流行毒序列及GenBank下载序列氨基酸同源性分别为90%、94%和96%左右,可见该次猪病疫情至少是由CSFV、PRRSV和PCV23种病毒混合感染引起。[结论]该研究可对当前危害养猪业混合感染疾病的流行病学研究和净化控制提供数据。     

猪繁殖与呼吸综合征病毒分子生物学及免疫学的研究进展

猪繁殖与呼吸综合征病毒是严重危害世界养猪业的病原,其分子生物学及感染机制的研究,对猪繁殖与呼吸综合征的预防和控制非常重要。笔者对猪繁殖与呼吸综合征病毒的病原学特性、分子生物学特征、获得性免疫和免疫调节与逃避机制等方面进行了综述,以期为该病的深入研究提供参考。     

Virus-directed protein synthesis in different animal and human cells

The relative proportions of viral gene products (viral proteins) that are synthesized in different types of animal cells infected with the same RNA virus inoculum were compared. The relative rates of synthesis of the various virus proteins late in infection were remarkably constant regardless of cell type infected. This was true in cell lines that produced only small amounts of virus and virus proteins, as well as in those that gave large yields of viruses and virus proteins.     

DNA of Rous sarcoma virus: its nature and significance

Purified preparations of Rous sarcoma virus (an avian tumor virus with an RNA genome) contain small amounts of double-stranded DNA. This DNA cannot be hybridized to viral RNA, but will reanneal completely with the DNA of avian cells. Extensive substitution of bromodeoxyuridine for thymidine in "viral" DNA does not photosensitize the biological activity of the virus. These observations indicate that the DNA associated with Rous sarcoma virus is derived from the DNA of the avian host cell, and is probably devoid of any function in the life cycle of the virus.     

Evolution of cell recognition by viruses

Evolution of receptor specificity by viruses has several implications for viral pathogenesis, host range, virus-mediated gene targeting, and viral adaptation after organ transplantation and xenotransplantation, as well as for the emergence of viral diseases. Recent evidence suggests that minimal changes in viral genomes may trigger a shift in receptor usage for virus entry, even into the same cell type. A capacity to exploit alternative entry pathways may reflect the ancient evolutionary origins of viruses and a possible role as agents of horizontal gene transfers among cells.     

猪繁殖与呼吸综合征病毒17-ZJ-HZ毒株的分离鉴定与分子流行病学分析

杭州某猪场断奶仔猪群出现高热、呼吸困难等症状,疑似猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)感染,3头病猪肺脏病变样本送本实验室检测,通过RT-PCR方法检测其病原核酸。肺脏匀浆液无菌处理接种到MARC-145细胞,细胞病变观察、Western-blot、间接免疫荧光等方法验证PRRSV病毒分离情况;RT-PCR方法分五段扩增获得全长病毒基因组序列,采用MEGA等软件分析该毒株的核苷酸序列以及GP5、NSP2氨基酸序列;分离病毒接种3日龄PRRSV阴性仔猪,评价该病毒的毒力。结果表明:该场送检样品为PRRSV阳性;成功分离得到17-ZJ-HZ病毒;获得15 325 bp的 PRRSV全基因组序列。序列分析表明,该毒株与经典北美株的NSP2存在典型的29+1个氨基酸的缺失,且进化分析归于HP-PRRSV亚群。攻毒60 h后猪只出现典型的PRRSV临床症状和病理变化,以上结果表明该毒株为高致病性PRRSV(highly pathogenic PRRSV, HP-PRRSV)的北美株。     

Review for Porcine Reproductive and Respiratory Syndrome Virus

Abstract Porcine reproductive and respiratory syndrome(PRRS)is the severest disease of pigs worldwide,caused by a highly genetically diverse RNA virus,called Porcine reproductive and respiratory syndrome virus(PRRSV).The research summarized the genome characteristics of PRRSV particles and the most updated knowledge of structure protein function,and introduced the intellectual of PRRSV transmission and host immune response,which is very important for prevention and control for PRRS.A report showed that mass vaccination can stabilize the immunity of the entire herd,and this is the first required step for a PRRS eradication plan.However,the attenuated live vaccines may not achieve a valid prevention.The final goal of the EU project is to develop new generation,efficacious and safe maker vaccines that can be adapted to temporary changes and geographical differences.Robinson reported that broadly antibodies could neutralize all rapidly evolving typeⅠand typeⅡviruses,while further studies are expected to elucidate mechanisms of neutralizing antibody production and maturation and to investigate conserved epitope targets of cross-neutralization in this rapidly evolving virus.     

2008-2011年浙江省猪主要病毒性疫病病原流行病学调查

为了解浙江省猪主要病毒性疫病的流行动态,采集近4年来临床病猪病料1118头份,采用PCR和RT-PCR方法进行猪主要病毒性疫病的病原检测.结果显示,PRRSV,CSFV,JEV,PCV2,PRV,PPV,PEDV和TGEV病原的平均感染率分别为51.71％,15.71％,27.16％,50.8％,1.99％,84.4％和9.0％.其中PRRSV,CSFV和PCV2每年都有较高的检出率,仍是浙江省猪场的主要病原;PRV和PPV近年来流行有所下降,该病已得到较好控制;2011年初发现流产病例中JEV的检出比例有明显升高,检出率高达39.29％;2011年2月在刚出生仔猪腹泻病例中PEDV检出率大大提高,造成严重损失.总之,浙江省猪场中PRRSV,CSFV和PCV2仍是防控的重点,但多病原感染或新变异株的出现也是近年来浙江省猪疫病复杂化的主要原因之一.     

Influenza virus effects on cell membrane proteins

During infection by influenza virus, viral proteins become firmly attached to (or part of) host cell plasma membrane, nuclear membranes, mitochondrial, and microsomal membranes. Purified virus particles contain less than I percent host cell protein. Virus envelope proteins completely replace host membrane proteins in those discrete spots on the plasma membrane from which progeny virions bud out.