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Infection with virulent biotypes of feline coronavirus (FCoV) can result in the development of feline infectious peritonitis (FIP), a typically fatal immune mediated disease for which there is currently no effective antiviral treatment. In this study we demonstrate the ability of small interfering RNA (siRNA) mediated RNA interference (RNAi) to inhibit the replication of virulent FCoV strain FIPV WSU 79-1146 in an immortalised feline cell line. A panel of eight synthetic siRNAs targeting four different regions of the FCoV genome were tested for antiviral effects. Efficacy was determined by qRT-PCR of intracellular viral genomic and messenger RNA, TCID50 infectivity assay of extracellular virus, and direct IFA for viral protein expression. All siRNAs demonstrated an inhibitory effect on viral replication in vitro. The two most effective siRNAs, targeting the untranslated 5' leader sequence (L2) and the nucleocapsid gene (N1), resulted in a >95% reduction in extracellular viral titre. Further characterisation of these two siRNAs demonstrated their efficacy when used at low concentrations and in cells challenged with high viral loads. Taken together these findings provide important information for the potential therapeutic application of RNAi in treating FIP.  相似文献   

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The inhibitory activities of various 8-difluoromethoxy-4-quinolone derivatives against feline immunodeficiency virus (FIV) replication in the chronically infected cell line P-CrFK were investigated. Certain derivatives were found to inhibit FIV production from P-CrFK cells in a dose-dependent manner without exhibiting cytotoxic effects at inhibitory concentrations. Based on this study, the structures important for anti-FIV activity are suggested to be (i) a carboxyl group at position C-3, and (ii) an aromatic modification at position 4 of the C-7 piperazinyl moiety.  相似文献   

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The appearance of non-cytolytic T cells that suppressed feline immunodeficiency virus (FIV) replication in vitro, and FIV-specific cytotoxic T cell (CTL) responses was compared in a group of seven, specific pathogen free (SPF) domestic cats following primary infection with the Glasgow(8) isolate of FIV (FIV(GL-8)). FIV proviral burdens were quantified in the blood and lymphoid tissues by real-time PCR. Non-cytolytic T cell suppression of FIV replication was measured by co-cultivating lymphoblasts prepared from the cats at different time-points during infection with FIV-infected MYA-1 cells in vitro. Non-cytolytic suppressor activity was detected as early as 1 week after infection, and was evident in all the lymphoid tissues examined. Further, this activity was present in subpopulations of T cells in the blood with normal (CD8(hi)) or reduced (CD8(lo)) expression of the CD8 molecule, and temporal modulations in non-cytolytic suppressor activity were unrelated to the circulating CD8(+) T cell numbers. Virus-specific CTL responses, measured by (51)Cr release assays, were not detected until 4 weeks after infection, with the emergence of FIV-specific effector CTLs in the blood. Throughout infection the response was predominantly directed towards FIV Gag-expressing target cells, and by 47 weeks after infection CTL responses had become localised in the lymph nodes and spleen. The results suggest that both non-cytolytic T cell suppression of FIV replication and FIV-specific CTL responses are important cellular immune mechanisms in the control of FIV replication in infected asymptomatic cats.  相似文献   

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针对猪繁殖与呼吸综合征病毒(PRRSV)JL/07/SW株GP5基因设计了3个RNA干扰靶位,构建shRNA表达质粒;将转染干扰质粒6 h后的MARC-145细胞接种病毒,并通过Real-time RT-PCR、TCID50、CPE、间接免疫荧光检测(IFA)对所设计的shRNA表达质粒的干扰效果进行评价;结果表明,构建的干扰质粒可以高效抑制PRRSV在MARC-145细胞中的复制,说明GP5基因的这3个干扰靶位可能是PRRSV复制所必需的。本试验为PRRSV复制及基因组功能研究、抗病毒药物开发和转基因动物研究奠定了基础。  相似文献   

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Vaccine protection has been achieved in cats against experimental infection with feline immunodeficiency virus (FIV). Such protection has been attributed to FIV-specific humoral immunity, as well as cellular immunity of unknown mechanism(s). Since cell-mediated immunity plays a crucial role in the clearance of viral infections, this study evaluated the role of FIV-specific CTL in vaccine prophylaxis. Cats were immunised with inactivated FIV vaccines, reported to have >90% vaccine efficacy. Significant levels of specific CTL activity were detected following the third immunisation. CTL activity persisted for several months and could be enhanced through a booster immunisation. The levels of CTL activity were comparable to those induced by a recombinant canarypoxvirus based FIV vaccine. These results suggest a possible role for CTL-mediated immunity in vaccine protection against FIV infection in cats.  相似文献   

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Natural or experimental feline immunodeficiency virus (FIV) infection in cats is often associated with hematologic abnormalities which are similar to those observed in human immunodeficiency virus (HIV) infected patients. To determine if cells in bone marrow are infected with FIV and whether severity of hematopoietic disorder is correlated with the level of viral infection, bone marrow tissues from ten experimentally and two naturally FIV infected cats were examined by in situ hybridization for presence of FIV RNA. Seven of the 12 FIV infected cats were also naturally or experimentally coinfected with feline leukemia virus (FeLV). FIV RNA was detected mainly in megakaryocytes and unidentified mononuclear cells in the bone marrow of cats that were sick and had marrow hypercellularity and immaturity. These included all cats in the acute phase of FIV infection and two of seven long term FIV infected cats. One long term FIV infected cat with lymphosarcoma was also positive for FIV RNA in bone marrow cells. The other four long term FIV infected cats were relatively healthy, with normal bone marrow morphology, and were negative for FIV infected cells. Bone marrow from three non-infected and two cats infected with FeLV alone were also negative for FIV RNA by in situ hybridization. We concluded that megakaryocytes and mononuclear cells were targets of the viral infection and that the presence of FIV RNA in cells of the bone marrow correlated with marrow hypercellularity and immaturity, and severity of illness.  相似文献   

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An in vitro model of acute and chronic infections with feline immunodeficiency virus (FIV) was used to examine the effect of two immunosuppressive agents, cyclosporin A (CsA) and tacrolimus (also known as FK506), on the inhibition of the replication of the virus and of apoptosis. Both drugs significantly suppressed virus production in a dose-dependent manner in acutely and chronically infected cells. The ability of FK506 to inhibit virus replication was much lower than that of CsA, and was accompanied by marked antiproliferative activity. Treatment of infected cells with either CsA or FK506 did not affect the rise of free intracellular Ca2+ but did protect the cells against apoptosis. Thus, the antiviral activity of CsA and FK506 makes these compounds promising candidates for the development of drugs suitable for the treatment of AIDS.  相似文献   

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研究慢病毒载体介导的RNA干扰对水牛CD14基因表达的影响,设计并筛选具有抑制作用的靶序列。将真核表达载体pDsRed-N1-buffaloCD14转染293细胞株,建立稳定表达水牛CD14基因细胞系。同时设计5条水牛CD14 shRNA(319/421/755/970/1 041)以及1条阴性对照序列(NC-1864),构建慢病毒重组质粒pSicoR-GFP-shRNA。采用磷酸钙沉淀法将三质粒共转染293T细胞包装慢病毒,并进行滴度测定。最后,通过对慢病毒感染的pDsRed1-N1-buffalo CD14-293细胞进行QRT-PCR检测,筛选具有抑制效果的shRNA。结果显示:在各感染细胞组中,外源水牛CD14基因mRNA的表达均受到不同程度的抑制,其中,CD14 shRNA-970靶点的干扰效率最高,达到79.3%(P<0.01)。成功筛选出具有较高抑制效果的水牛CD14 shRNA靶序列,为研究CD14基因在布氏杆菌所致炎症反应中的作用,建立家畜布氏杆菌病防治新方法奠定了基础。  相似文献   

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靶向狂犬病病毒N基因shRNA抑制狂犬病病毒复制的研究   总被引:1,自引:0,他引:1  
为探讨小干扰RNA(siRNA)对狂犬病病毒(RV)复制的干扰作用,以RVN基因为靶向目标,设计合成4对编码siRNA的DNA序列,然后分别连接到载体pRNATU6.3-Hygro上,转染BHK细胞,在潮霉素-B抗性压力下筛选出4个阳性细胞株(BHK-N1、BHK-N2、BHK-N3和BHK-N4)。用100TCID50CVS-11毒分别感染24孔板内的上述细胞,利用Real-time RT-PCR、半数细胞培养物感染量(TCID50)、直接免疫荧光和Western blot检测抑制效率。接毒后48 h,在BHK-N1、BHK-N2、BHK-N3、BHK-N4细胞株中,Real-time RT-PCR检测到各细胞株均在不同程度上抑制了RV的增殖,其中BHK-N2、BHK-N1抑制效率高,分别为99%、67.72%,而BHK-N3、BHK-N4仅为38.59%和11.33%,抑制效果较弱;TCID50检测病毒数量比空载体表达细胞毒价分别低24、96.2、2.14和1.1倍;直接免疫荧光检测表明,4株细胞中RV含量为病毒对照的31%、1%、54%、82%,即BHK-N1、BHK-N2对病毒的沉默作用较强;Western blot结果显示BHK-N1、BHK-N2细胞株中RV N蛋白条带明显减弱。4种检测结果均表明BHK-N1和BHK-N2能有效干扰RV的复制。本研究在细胞水平筛选出具有高效抑制RV复制的2个靶位点N-489和N-701,为RV的基因功能研究、抗病毒药物的开发奠定了基础。  相似文献   

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Bovine viral diarrhea virus (BVDV) is a ubiquitous viral pathogen that affects cattle herds' worldwide causing significant economic loss. The current strategies to control BVDV infection include vaccination (modified-live or killed) and control of virus spread by enhanced biosecurity management, however, the disease remains prevalent. With the discovery of the sequence-specific method of gene silencing known as RNA interference (RNAi), a new era in antiviral therapies has begun. Here we report the efficient inhibition of BVDV replication by small interfering (siRNA) and short hairpin RNA (shRNA)-mediated gene silencing. siRNAs were generated to target the 5' non-translated (NTR) region and the regions encoding the C, NS4B and NS5A proteins of the BVDV genome. The siRNAs were first validated using an EGFP/BVDV reporter system and were then shown to suppress BVDV-induced cytopathic effects and viral titers in cell culture with surprisingly different activities compared to the reporter system. Efficient viral suppression was then achieved by bovine 7SK-expressed BVDV-specific shRNAs. Overall, our results demonstrated the use of siRNA and shRNA-mediated gene silencing to achieve efficient inhibition of the replication of this virus in cell culture.  相似文献   

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The envelope (Env) gene V3-V5 regions of the feline immunodeficiency virus (FIV) encode the neutralizing epitopes. Since mutations in these regions induce resistance to viral neutralizing antibodies, they may influence the effects of vaccines. To examine the in vivo mutation rate in these regions, we cloned cDNA for the Env gene V3-V5 regions from the PBMC of experimentally FIV-infected cats, and compared the deduced amino acid sequences. Blood or plasma from an FIV Shizuoka strain-infected cat was inoculated into a second group of SPF cats, and their blood or plasma was inoculated into the third group. The amino acid sequence encoded by the viral gene of the first cat was compared with those encoded by the viral genes of a total of eight cats in the second and third groups (two and six cats, respectively). The amino acid sequences in two cats in the second and third groups were 100% homologous and in one cat in the third group was 98.3% homologous to that in the first infected cat. Five cats had the same sequence, which was 97.8% homologous to that in the first infected cat. Three kittens, born 2 months after the inoculation of the FIV Aomori-2 strain into the mother cat, were anti-FIV negative at 4 weeks after birth, but became seropositive at 33 weeks after birth, confirming FIV infection. Comparison of the encoded amino acid sequences of the viral gene in two cats at 48 weeks after birth showed 100% homology to that of the virus inoculated into the mother cat, and the remaining one cat had a single residue substitution, resulting in 99.4% homology. These results suggest that the FIV Env gene V3-V5 regions are stably maintained for at least 1-2 years after infection.  相似文献   

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The infection of the feline T-lymphocyte cell line FeT-J with the feline immunodeficiency virus (FIV) Petaluma strain led to the establishment of nonvirus-producing cells. One clone (C15) obtained by limiting dilution was found to express FIV in response to chemical inducers of retroviruses. The chemical treatment of C15 cells led to not only FIV protein synthesis but also an augmentation of viral production. Examination of the C15 cell derivatives obtained by recloning revealed that 10-40% of treated cells constitutively expressed FIV antigens, whereas 100% with expressed FIV antigen in response to the inducer. Chemical induction resulted in more than a 100-fold increase in infectious viral production. The results suggest that a majority of FeT-J cells that are infected with FIV exist in a non-productive state. Establishing a cell line that can be non-productively infected by FIV may help determine the mechanisms of FIV latency.  相似文献   

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Li YC  Kong LH  Cheng BZ  Li KS 《Avian diseases》2005,49(4):562-573
Three plasmid constructs were prepared that express small interfering RNAs (siRNAs) targeted to sequences encoding the ribonucleoprotein member, nucleoprotein (NP) and/or PA, of influenza virus genome. The antiviral properties of siRNAs against the H5N1 strain of influenza virus were studied by evaluating their capacity to silence expression of target genes as well as their effect on influenza virus-induced apoptosis in Madin-Darby canine kidney cells, chicken embryo fibroblast cells, and embryonated chicken eggs in a transient replication model. The results demonstrated that all three siRNAs expressing plasmids efficiently transcribed the short hairpin RNAs and inhibited expression of the NP or PA proteins measured by northern blot and western blot analyses, respectively, in the transfected cells. We also found that the integrated siRNA expression plasmid pEGFP/NP+PA, which we constructed for the first time to synchronously target NP and PA segments of the influenza virus genome, could more efficiently inhibit synthesis of influenza virus detected by cytopathogenic effects, hemagglutinin, and plaque-forming unit assays in the transfected cells. Furthermore, the integrated siRNA expression plasmid pEGFP/NP+PA could remarkably interrupt the cellular apoptotic course caused by influenza virus, which protected infected cells from apoptotic damage. In contrast, a control siRNA expression plasmid, pEGFP/HK, could neither inhibit the protein expression and production of influenza virus nor interrupt the cell apoptotic course mediated by influenza virus. These results demonstrate that RNA interference (RNAi) can be used to inhibit protein expression and replication of influenza virus and that RNAi treatment holds potential as a new approach to prevent avian influenza.  相似文献   

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