A highly sensitive heminested RT-PCR assay for the detection of citrus psorosis virus targeted to a conserved region of the genome

Psorosis is a widespread and damaging disease of citrus in many parts of the world. The causal agent is a multipartite virus with RNA genome present in very low concentration in infected citrus tissue. Diagnosis is made by biological indexing on indicator citrus seedlings, but it is a slow and costly procedure and therefore it is not used generally. No sensitive wide-spectrum assay for Citrus Psorosis virus (CPsV) has been reported based on RT-PCR. A highly sensitive heminested RT-PCR assay is described for the detection of CPsV. Fragments of 313 bp amplified from RNA 1 of different isolates were cloned and sequenced. Very high homology was found among six isolates from the citrus producing region of Argentina: 96.6-100% in nucleotide sequence. The consensus sequence obtained was used for the design of the primers for heminested PCR assay. It has been tested on different Argentine isolates, employing various methods for RNA extraction from infected tissue. This test is able to detect CPsV in dilutions of 10(10) of the original sample.     

Comparison of the effects of rabies virus infection and of combined interferon and poly(I).poly(C) treatment on the levels of 2',5'-adenyladenosine oligonucleotides in different organs of mice

Intracellular levels of 2',5'-adenyladenosine oligonucleotides were analyzed in different organs of mice during the course of a rabies virus infection. Phosphorylated and nonphosphorylated 2',5'-adenyladenosine oligonucleotides were measured by radioimmunoassay and analyzed further by HPLC. As the infection progressed, concentrations of phosphorylated 2',5'-adenyladenosine oligonucleotides increased strongly, reaching their maxima late in the infection. In contrast, concentrations of the nonphosphorylated 2',5'-adenyladenosine oligonucleotides decreased. A similar phenomenon was observed in spleens analyzed at intervals after treatment of noninfected mice with interferon and poly(I).poly(C) and to a lesser extent after treatment of noninfected mice with interferon and poly(I).poly(C) and to a lesser extent after treatment with poly(I).poly(C) alone, but not after treatment with interferon alone. The products which accumulated during virus infection were primarily phosphorylated dimers whereas during combined interferon and poly(I).poly(C) treatment, the entire range of phosphorylated molecules from dimer to pentamer was present. These data show that infection of mice with rabies virus provokes both the induction and the activation of 2-5A synthetase, as does interferon and poly(I).poly(C) treatment. However, our data indicate that the intracellular products are different in the two situations: the species active on the nuclease were only detected in interferon- and poly(I).poly(C)-treated mice. The absence of molecules able to activate the 2-5A-dependent nuclease in virus-infected mice might well be one of the reasons why the interferon system is ineffective in rabies virus infection.     

Ante mortem diagnosis of human rabies using saliva samples: comparison of real time and conventional RT-PCR techniques.

BACKGROUND: Rabies is an enzootic and fatal disease and is still a major problem in developing countries. Ante mortem diagnosis in human cases is necessary for medical management of the patient and to ensure appropriate post-exposure treatment of contacts. Both conventional RT-PCR and Real time PCR (TaqMan) have been described for the detection of rabies virus RNA from saliva and tissue respectively, however to date, there have been no studies comparing conventional and real time PCR assays for detection of rabies virus nucleic acid using saliva samples for ante mortem diagnosis. OBJECTIVES: In this study, we evaluated the utility of conventional RT-PCR and SYBR Green I Real time PCR in the ante mortem diagnosis of rabies using saliva samples. STUDY DESIGN: Saliva samples collected from twenty-four patients presenting with typical clinical manifestations of rabies were tested in the two assays. RESULTS: Amongst the 24 samples tested, 21 samples (87.5%) were positive by either of the two molecular methods. Of these 21, rabies virus RNA was detected in 6/21 in the conventional RT-PCR assay while SYBR Green I Real time PCR could detect RNA in 18/21 samples. CONCLUSION: Real time PCR assay was more sensitive than conventional RT-PCR assay (sensitivity 75% versus 37%, p=0.0189). This study highlights the utility of molecular diagnostic tests in establishing ante mortem diagnosis of rabies using saliva samples within a few hours.     

狂犬病毒3aG株糖蛋白基因在人5型重组腺病毒中的表达研究

目的 构建表达狂犬病毒糖蛋白基因（ＧＰ）的重组人腺病毒。方法 克隆狂犬病毒疫苗株ＧＰ基因并测序，将其插入Ｅ３区缺失的Ａｄ５载体，置于Ｅ３区早期启动子的控制下，通过同源重组，蚀斑纯化，筛选表达ＧＰ的重组人腺病毒。用ＥＬＩＳＡ法检测表达的糖蛋白，快速荧光灶抑制试验（ＲＦＦＩＴ）法测定此重组病毒免疫小鼠后产生的中和抗体。结果 获得的３ａＧ株基因的开放读码框为１５７５个核苷酸，编码５２４个氨基酸；经同源重     

Molecular epidemiology of rabies in Guangxi Province, south of China.

BACKGROUND: Surveillance data for rabies in Guangxi Province in China showed that human rabies cases have gradually increased since 1996. OBJECTIVE: To evaluate the epidemiology of rabies at the molecular level and provide suggestions for effective prevention of rabies in Guangxi. STUDY DESIGN: Since 2000, 1569 brains from suspected rabid animals were collected from different areas of Guangxi. Rabies virus was isolated from 42 samples. RT-PCR was used to amplify a 455 nucleotide segment of the 3'-terminal of the N gene. The sequencing data from that segment was used for phylogenetic analysis. RESULTS: Nucleotide homology comparisons and phylogenetic tree analysis based on this sequence indicated that all the rabies virus isolates from Guangxi belonged to genotype 1 and could be divided into four groups. Groups I, II and IV included 23, 10 and 8 isolates, respectively. These had nucleotide homologies of 97.1-100%, 98.2-100% and 99.1-99.6%, respectively. Only the GXN119 strain belonged to group III. Group I had two group-specific mutations: T90N and E110D. Group II had one group-specific mutation of T42S. CONCLUSIONS: This study showed that rabies virus isolates from Guangxi have a close genetic relationship and topographical distribution.     

Immune response to the nominal phosphoprotein of rabies virus.

The immune response to the nominal phosphoprotein (NS protein) of rabies virus was investigated with the use of a vaccinia recombinant virus that expressed the NS protein of a fixed rabies virus strain. Mice of the H-2k haplotype that were injected with either live rabies virus or the vaccinia recombinant virus developed a strong cytolytic T-cell response specific for the NS protein. This response was under immune response (Ir) gene control. The NS protein as presented by the vaccinia recombinant virus was a poor inducer of rabies virus-specific T-helper (Th) cells and B cells in the H-2k background. Furthermore, mice of the H-2k haplotype could not be protected by vaccination with the vaccinia recombinant virus expressing the NS protein, although protection in outbred mice was partial and incomplete. These data indicate that cytolytic T cells to the NS protein of rabies virus are insufficient to protect mice against a challenge with rabies virus.     

狂犬病毒融合糖蛋白DNA疫苗及免疫效果的研究

目的：构建含两种狂犬病毒疫苗株的融合糖蛋白基因DNA疫苗并对小鼠的免疫效果进行评价.方法：用RT-PCR法分别扩增和分离出SRV9株和CTN株的狂犬病毒糖蛋白部分表位的基因（SRV9毒株的1～252氨基酸和CTN毒株253～524氨基酸）,构建含融合G蛋白基因的DNA疫苗质粒VR1055-SRV9CTN.碱裂解法大量提取重组质粒并经Sepharose 4FF柱层析纯化后直接肌肉注射免疫NIH小鼠,用ELISA法和淋巴细胞转化实验分别检测质粒DNA疫苗诱导小鼠产生抗狂犬病毒的体液免疫和细胞免疫效果.CTLL-2依赖细胞株/MTT比色法进行IL-2活性测定.结果：VR1055-SRV9CTN DNA疫苗具有较好的诱生狂犬病毒抗体能力.诱导细胞免疫方面,质粒VR1055-SRV9CTN DNA疫苗和空载体对照组的ConA刺激指数存在显著性差异（t=7.201,P=0.000）.小鼠血清中的IL-2活性测定表明DNA疫苗组显著高于空载体组（t=21.616,P=0.000）.CVS株RV脑内攻击保护实验中,疫苗组和对照组小鼠存活率分别为63%、25%,二者间差异具有显著性（t=7.065,P=0.008）.结论：含狂犬病毒糖蛋白基因VR1055-SRV9CTN DNA疫苗既能诱导体液免疫又能诱导细胞免疫,具有较好的免疫保护效果.     

Pathogenesis of rabies virus from a Danish bat (Eptesicus serotinus): neuronal changes suggestive of spongiosis

Summary Rabies virus strains isolated from a European bat (Eptesicus serotinus) in Denmark (DBV), a North American big brown bat (Eptesicus fuscus) in New York State (NY-bat), and a human in South Africa (Duvenhage strain (DUV-1) were studied by using a panel of monoclonal antibodies and by inoculating mice, cats, and dogs. The ten Danish virus isolates from the same bat species reacted identically with a panel of monoclonal antibodies. Immunofluorescence, monoclonal antibody, and histopathologic studies showed that the Danish bat isolates were similar to Duvenhage, and to some degree, to classical rabies virus. All isolates produced fatal infections in mice when inoculated by the intracerebral, footpad, and oral routes. Dogs and cats inoculated intracerebrally with the DBV and DUV-1 virus strains died of rabies-like illnesses within 10 days. Although no dogs that were inoculated intramuscularly or intravenously showed signs of disease, all developed neutralizing antibodies and resisted challenge with lethal dose of street rabies virus. All dogs inoculated with the NY-bat virus, with the exception of those inoculated intravenously, showed classical signs of rabies and one of the intramuscularly inoculated dogs recovered. Cats inoculated intramuscularly also died of rabies-like illness within 15 days. At necropsy, rabies antigen was detected by immunofluorescence in frozen sections of several organs, including brain and salivary glands. Histopathologic and electron microscopic studies of the central nervous system of mice, dogs and cats that died of DBV infection showed neuronal cytoplasmic changes considered to be a form of spongiosis.     

小鼠对表达狂犬病毒3aG株糖蛋白的重组复制缺陷型腺病毒的免疫应答

目的研究表达狂犬病毒3aG株糖蛋白(GP)的重组复制缺陷型腺病毒Ad/GP＇及Ad/GP免疫小鼠后所产生的特异性体液免疫应答,体外脾细胞增殖反应,及免疫小鼠对狂犬病毒致死性颅内攻击的保护力。方法1×10     

湖南3县(市)狂犬病病毒分子生物学研究

目的研究湖南省狂犬病高发区和无病例区动物携带狂犬病的分子生物学特征。方法用直接免疫荧光法检测犬唾液及犬、猫脑标本，以RT．PCR法复核阳性进行遗传学分析。结果武冈市和洞口县送检的82只和17只犬中，分别有12只和1只检测到狂犬病毒抗原与核苷酸阳性，阳性率分别为14．63％和5．88％。凤凰县67份大脑标本未检测出病毒。28份猫脑组织标本也未检测出狂犬病毒。用RT-PCR法扩增阳性大脑组织（编号为Wg13，Dk13）的狂犬病毒N基因，两株病毒之间核苷酸与氨基酸的同源性分别为99、4％及99．1％；Wg13株与中国疫苗株CTN株和aG株的核苷酸同源性（氨基酸）分别为89．4％（98．2％）、86．1％（95．1％）；Dk13株与中国疫苗株CTN株和aG株的核苷酸同源性分别为89．1％（98．0％）、86．1％（94．9％）。与其他国家分离到的狂犬病毒相比，两株病毒与印度尼西亚的同源性最大，分别为92．8％、93．2％，而与印度、日本及斯里兰卡等其他国家同源性相对较小。结论两株狂犬病毒均为I型狂犬病毒。其N基因的核苷酸序列与当前使用的疫苗株相比，两株病毒与CTN疫苗株分在同一组，同源性较大。     

Extraneural organ involvement in human rabies.

Human rabies is a fatal encephalomyelitis. After the development of the central nervous system infection, there is centrifugal spread of the rabies virus to extraneural (systemic) organs. With histochemical staining and localization of rabies virus antigen (RVA) with immunoperoxidase staining, we have examined tissue sections of organs from 14 postmortem pediatric and adult cases of human rabies acquired in Mexico and the People's Republic of China. RVA was found in nerve plexuses in multiple organs, including the gastrointestinal tract. RVA was observed in muscle fibers of the heart, tongue, and larynx. RVA frequently was observed in the adrenal medulla with an associated inflammatory reaction. Minor salivary glands of the tongue contained RVA and major salivary glands showed RVA in plexuses, but not in either acini or ducts. Epithelial cells of the tongue and taste buds were occasionally infected. RVA was observed in hair follicles of the skin and rarely in pancreatic islets. The infection of extraneural organs was sometimes, but not always, associated with an inflammatory reaction. These findings indicate that centrifugal spread of rabies virus to extraneural organs occurs frequently in human rabies.     

Viral RNA in the bloodstream suggests viremia occurs in clinically ill rabies-infected mice

Data regarding the occurrence of a viremia during rabies virus infections are contradictory. Here, we attempted to clarify the dissimilar results using a qualitative TaqMan PCR assay to detect viral RNA in blood of mice that had been injected intramuscularly with rabies virus. Viral RNA was detected at two different intervals. Initially, RNA was present in blood of 30/32 (94%) mice, from 1h to 2 days after injection of virus. The RNA in the blood at this time most likely resulted from trauma to blood vessels at the injection site and leakage of the inoculated virus into the circulation. Thereafter, from 3 to 30 days, viral RNA was undetectable in the blood of 37 mice that remained free of clinical disease. However, and more importantly, viral RNA was detected again in 21/25 (84%) mice that became clinically ill and were exsanguinated 2-4 days after the onset of paralysis. The presence of viral RNA in blood of the clinically ill mice might have been due to an escape of virus into the bloodstream as a result of viral replication induced injury in the central nervous system and other tissues. Anti-rabies virus neutralizing antibody was detected in sera of 11/21 (52%) clinically ill mice whose blood was positive for rabies viral RNA. The presence of viral RNA in the bloodstream of mice that developed clinical rabies suggested that a viremia might occur in rabies-infected mice. Thus, the current opinion that a viremia does not occur in experimental or natural rabies infections of other species might need to be re-evaluated.     

International interlaboratory trials on rabies diagnosis: an overview of results and variation in reference diagnosis techniques (fluorescent antibody test, rabies tissue culture infection test, mouse inoculation test) and molecular biology techniques

Interlaboratory trials on rabies diagnosis were organised in 2009 and in 2010 by the European Union Reference Laboratory (EURL) for rabies. In 2009, two panels of virus samples were sent to participating laboratories to compare results on reference diagnosis techniques and on RT-PCR. A single panel was sent in 2010 to test FAT (fluorescent antibody test), RTCIT (rabies tissue culture infection test) and RT-PCR techniques. The virus panels included the RABV, EBLV-1, EBLV-2 and ABLV strains. Results revealed that laboratories produced the highest proportion of concordant results using RT-PCR (90.5%) and FAT (87.1%), followed by RTCIT (70.0%) and MIT (35.0%) in 2009 and in FAT (85.0%) and RT-PCR (80.6%) followed by RTCIT (77.3%) in 2010. Errors were only observed in bat strains (i.e. none in the RABV strain) for the RT-PCR or FAT techniques, highlighting the need to improve diagnosis most specifically in such strains. RT-PCR was the technique showing the lowest rate of false negative results in either trial year, while RTCIT and MIT (performed in 2009 only) were the techniques with the lowest proportion of false positive results. Nevertheless, the FAT technique represented a good compromise with both satisfactory sensitivity and specificity, as only a few false positive (1.6% in 2009, 5.8% in 2010) and false negative results (1.6% in both 2009 and 2010) were detected. The analysis of technical questionnaires describing the protocols used by participating laboratories revealed variation in the methods used that may induce inconsistencies in the results. In this study, the number of readers for FAT slide examination was identified as a factor affecting significantly the results of laboratories, suggesting that two independent readers are necessary for routine rabies diagnosis. Our findings highlight the need for all rabies diagnostic laboratories to improve harmonisation of procedures.     

冰冻切片染色法观察重组狂犬病病毒对乳鼠脑的感染和定位

目的冰冻切片染色法观察重组狂犬病病毒对乳鼠脑的感染和定位。方法将本实验室构建并拯救成功的人用狂犬病疫苗株重组病毒（CTN—GFP）脑内接种1日龄乳鼠和4周龄成年鼠,待感染乳鼠发病后至濒死期,通过心内灌流方法固定并制作脑组织冰冻切片,观察重组病毒在感染鼠的大脑海马组织中的绿色荧光蛋白的表达及分布。结果DAPI将所制作的冰冻切片中脑组织内细胞的胞核染成蓝色,在共聚焦显微镜下观察到受感染乳鼠的脑组织海马回位置有大量绿色荧光蛋白的表达。结论通过制作脑组织冰冻切片的方法可以清楚的观察到病毒的感染及其在海马回中的位置,同时为追踪病毒在体内的移行过程提供了一种新方法。