C亚型SHIV-XJ02170在中国恒河猴体内传代研究

目的 了解SHIV-XJ02170病毒在中国恒河猴体内传代过程中病毒学和免疫学变化特点,构建适用于我国艾滋病疫苗评价的C亚型SHIV/中国恒河猴模型.方法 将SHIV-XJ02170感染性全长质粒转染293T细胞制备病毒,后肢静脉途径在中国恒河猴体内传3～4代.传代过程中采用流式细胞术检测外周血CD4/CD8比值,分析病毒致病能力的变化.实时荧光定量RT-PCR方法 检测SHIV病毒载量,了解病毒学变化特点.同时,利用ELISA和ELISPOT方法 分析病毒传代过程中体液和细胞免疫学变化特点.结果 SHIV-XJ02170病毒传代过程中,CD4/CD8比值未表现出剧烈的下降特点.线路3传代中急性期血浆病毒载量峰值和Setpoint值表现出连续上升的趋势.病毒感染恒河猴后可诱导较强的体液和细胞免疫应答.同时,病毒载量和交叉抗体滴度之间表现出显著的正相关关系.结论 SHIV-XJ02170病毒在中国恒河猴传代后未出现致病性突变株,但是表现出毒力上升的趋势.SHIV-XJ02170/中国恒河猴模型将在我国艾滋病疫苗有效性评价中发挥重要作用.     

登革热病毒RNA实时荧光定量RT-PCR检测方法的建立

目的建立TaqMan探针实时荧光定量RT-PCR方法,测定登革热病毒（DV）及DV病毒的RNA拷贝数。方法利用TaqMan探针,建立实时荧光定量RT-PCR方法,通过对登革热病毒RNA定量外标准品的定量分析,优化反应体系,检测TaqMan探针实时荧光定量RT-PCR方法的灵敏度、特异性和重复性。结果该方法检测灵敏度可达1×103copies/mL,特异性及重复性良好,对同一样品进行5次重复检测,其循环阈值的平均标准偏差为0.792。结论TaqMan探针实时荧光定量RT-PCR法特异性、敏感性高,稳定性好,可用于定量测定登革热病毒及DVRNA载量。     

SHIV-XJ02170在中国恒河猴体内传代过程中env基因变异研究

目的 研究SHIV-XJ02170在中国恒河猴体内传代过程中env基因序列变异的特点.方法 应用聚合酶链反应(PCR)和逆转录聚合酶链反应(RT-PCR)分别对各代动物SHIV-XJ02170病毒载量峰值时间点全血前病毒DNA gp160基因和血浆病毒RNA gp120基因进行扩增.GP160基因PCR产物直接进行测序分析,gp120 RNA扩增产物连接T载体后每份样品挑选18个克隆测序,分析传代过程中病毒的基因距离(divergence,diversity)的变化规律及病毒基因进化的特点.结果 SHIV-XJ02170在传代过程中基因连续进化并且进化的方向和病毒传代的顺序完全一致,基因距离总体上表现为逐步扩大的趋势,病毒传代早期存在明显的"瓶颈效应".氨基酸序列分析发现V3环顶端四肽和辅助受体在传代过程中未发生改变.结论 SHIV-XJ02170经过中国恒河猴体内传代后基因距离出现明显扩大过程,且按照传代的顺序发生连续的基因进化.这从分子水平上部分解释了 SHIV-XJ02170经猴体传代出现毒力增强的原因.     

Kadipiro病毒TaqmanReal—timePCR检测方法的建立

目的利用TaqManReal—timePCR技术，建立Kadipiro病毒（KDV）实时荧光定量PCR检测方法。方法根据GenBank发表的KDV基因序列资料分析结果，在其第12片段基因区段设计KDV特异引物与探针，利用14株不同科属病毒核酸验证方法特异性，重复实验检验方法稳定性，利用体外转录的定量RNA标准品建立基因拷贝数定量分析模型。结果引物与探针具有良好的特异性，同一样品重复检测D值的变异系数均〈1．8％，定量分析模型的灵敏度为100拷贝／反应。结论建立了一种特异、灵敏、高效的KDV一步法TaqManReal-timePCR检测方法，为今后该病毒的监测与研究工作提供技术手段。     

LNA探针同时检测人副流感病毒1,2,3型多重荧光定量RT-PCR方法的建立

目的 人副流感病毒1,2,3型是呼吸道感染的主要病原.本研究建立了特异、快速、灵敏的多重荧光定量RT-PCR方法用于人副流感1,2,3型病毒临床标本检测.方法 针对人副流感1,2,3型病毒设计特异性引物探针,优化荧光RT-PCR反应条件.应用体外转录方法分别制备人副流感1,2,3型病毒的标准品.验证荧光定量RT-PCR方法的特异性,敏感性和稳定性.结果 该方法对人副流感1,2,3型病毒核酸检测有高度特异性,检测的灵敏度HPIV1为10个拷贝,HPIV2为100个拷贝,HPIV3为100个拷贝.可从临床患者鼻咽吸出物标本中直接检出.结论 本研究建立的LNA探针同时检测人副流感病毒1,2,3型多重荧光定量RT-PCR方法具有较高的特异性和敏感性.适用于临床早期诊断和实验室病原谱筛查.     

马尔堡、埃博拉病毒双重荧光定量PCR检测方法的建立

目的 建立一种快速、敏感、特异的双重实时荧光定量PCR方法,可同时检测马尔堡病毒和埃博拉病毒.方法 通过序列比对挑选出两种病毒基因组中高度保守的序列,分别设计引物及Taqman探针,两条探针分别标记FAM和Texas Red荧光报告基因,建立双重实时荧光定量PCR反应体系.结果 双重荧光定量PCR方法检测两种病毒阳性标准品的灵敏度分别为30.5拷贝/μl和28.6拷贝/μl,通过检测日本脑炎病毒、黄热病毒、登革热病毒无交叉反应,有较好的灵敏度和特异性.结论 建立了马尔堡、埃博拉病毒双重荧光定量PCR检测方法,实现了两种病毒同时实时定量检测,在传染病防控领域有较好的应用前景.     

阿瓦朗病毒和休斯病毒实时荧光RT-PCR检测方法研究

目的建立可以检测阿瓦朗病毒(Avalon virus,AVAV)和休斯病毒(Hughes virus,HUGV)两种内罗病毒的实时荧光定量RT-PCR检测方法,并进行初步的评价。方法收集、整理、比对、分析在公共数据库发布的两种病毒基因组核苷酸序列,确定检测靶标,设计特异性引物、探针,优化检测程序,建立实时荧光定量RT-PCR检测方法。利用体外转录技术制备的模拟样本、其他病毒感染标本、病毒株和正常人血标本比较评价所建方法的检测限、特异性、重复性特征。结果所建实时荧光定量RT-PCR检测方法可有效扩增检测AVAV和HUGA靶标RNA,检测限分别约为20拷贝/μl和70拷贝/μl,检测科萨努尔森林病毒、乙型流感病毒BV和BY型、甲型流感病毒H3N2、黄热病毒、乙型脑炎病毒、克里米亚-刚果出血热病毒、发热伴血小板减少综合征、内罗毕羊病毒和塔西那病毒样本无非特异性扩增,两种内罗病毒相互间无交叉反应,重复性比较分析显示变异系数小于2%。结论本研究建立的检测AVAV和HUGV的实时荧光定量RT-PCR方法,可用于临床样本检测和媒介生物、宿主动物标本筛查,便于病原的快速识别和疾病诊断。     

H9N2禽流感病毒一步法双重荧光RT-PCR检测方法的建立

目的 建立一种可同时检测禽流感病毒H9N2的HA和NA基因一步法双重荧光RT-PCR方法.方法 针对H9N2禽流感病毒的HA和NA基因保守区,设计相应的特异性引物以及探针,优化检测体系及反应条件,建立一步法双重荧光定量RT-PCR方法.对该方法的灵敏度、特异性、稳定性进行验证与评估,并对家禽粪便标本进行应用检测,以单重实时荧光RT-PCR方法作为参照,检测结果不一致的样本采用测序进行验证.结果 该方法特异性强,与H1、H3、H5、H7亚型禽流感病毒、鸡新城疫及鸡传染性支炎病毒均无交叉反应,对HA和NA基因的最低检出限分别可达50拷贝/μL和25拷贝/μL,组间与组内的变异系数在0.20 ～0.79％之间.对82份粪便标本进行检测,H9N2禽流感病毒的阳性率为8.14％ (7/82),与单重实时荧光RT-PCR法检测结果一致.结论 该方法特异性强、灵敏度高、稳定性好,可应用于临床禽流感样本的检测.     

一种可用于溶瘤病毒M1体内组织定量的TaqMan RT-qPCR检测法的建立与评价

目的:监测溶瘤病毒M1在组织中的传播情况,以更好地控制给药剂量,确保安全性。方法:建立一种基于TaqMan的实时定量PCR检测法,用于对组织中溶瘤病毒M1的检测和定量,并检测静脉注射病毒后多种实验动物体内的病毒载量和分布。结果:我们以一对特异的引物(Q3)和标准RNA开始SYBR Green RT-qPCR研究。通过优化实验方法发现当退火温度高于62℃时可降低基质效应,但却影响了扩增效率。因此我们建立了一步法TaqMan RT-qPCR实验,重新设计了一对Q3短引物(Q3S)。运用一步TaqMan RT-qPCR检测法和Q3S引物,在混有SD大鼠或食蟹猴基质RNA的背景下,均能特异性检测到低拷贝数的标准RNA。经验证,该方法适用于检测M1病毒在小鼠、SD大鼠和食蟹猴体内的组织分布。结论:利用Q3S引物构建的TaqMan一步法RT-qPCR能够定量检测不同动物不同组织样品中的M1病毒,具有特异性和敏感性,可进一步应用于临床样品的检测。     

Highly sensitive TaqMan RT-PCR assay for detection and quantification of both lineages of West Nile virus RNA.

BACKGROUND: Starting in 1999, the West Nile virus (WNV) epidemic represents the largest outbreak of arboviral encephalitis ever recorded in the U.S. The effective means to determine an infection are detection of viral nucleic acid and/or viral specific immunoglobulin, IgM and/or IgG. OBJECTIVE: To develop a highly sensitive and specific TaqMan RT-PCR assay for the detection and quantification of WNV RNA of lineage 1 and lineage 2. STUDY DESIGN: A TaqMan RT-PCR primer-probe was designed to perfectly match target sequences of all sequenced WNV strains and isolates, which added a layer of protection against false-negative results due to strain variability. In addition, the inclusion of a low level RNA internal control (IC) in the assay increased the precision and accuracy of the assay. RESULTS: By optimizing the RNA preparation procedure for increased WNV RNA recovery, together with optimizing the primer-probe and TaqMan conditions for improved amplification efficiency, we developed a highly sensitive assay with the detection limit of 10 copies/mL. To evaluate the assay, we tested plasma samples from 12 transfusion-transmitted implicated cases in 2002 and from 68 positive blood donors in 2003. All tested specimens were WNV positive. The viral load of 68 positive blood donor samples collected in 2003 ranged from 10 copies/mL to 67,000 copies/mL with a mean of 8100 copies/mL. Furthermore, high sensitivity of the assay was achieved without compromising specificity. All 100 routine donor samples tested negative. CONCLUSIONS: The assay results demonstrate that our in-house TaqMan RT-PCR procedure can detect and quantify WNV RNA of lineage1 and lineage 2 in human plasma with high sensitivity and specificity.     

CD4+ lymphocytopenia in acute infection of Asian macaques by a vaginally transmissible subtype-C,CCR5-tropic Simian/Human Immunodeficiency Virus (SHIV)

An R5-tropic SHIV(CHN19P4) was previously generated using a primary HIV-1 subtype-C envelope. We have further characterized this SHIV in two species of macaques. To determine whether this isolate is transmissible vaginally, female pig-tailed macaques were inoculated with 2 x 10(3) TCID50 of SHIV(CHN19P4) by the vaginal route. Animals became infected with a high peak plasma viremia (>10(7) viral copies/mL) and rapid seroconversion. The viremia was accompanied by CD4+ lymphocytopenia in the gut lamina propria lymphocyte (LPL) population. Comparable CD4+ T-cell loss was not seen in peripheral blood and colonic lymph nodes. These findings demonstrate a unique R5-tropic SHIV that can be used to study envelope-related issues in vaginal transmission of the most prevalent subtype of HIV-1. We also found that rhesus macaques intravenously inoculated with 1 x 10(3) TCID50 of SHIV(CHN19P4) became infected and showed CD4+ lymphocytopenia in the gut LPL population. Despite inactivation of the vpu gene in SHIV(CHN19P4), the virus appears to target mainly gut-associated lymphoid tissues during the initial stage of infection as has been described for SHIV(SF162P), another R5-tropic (subtype B) recombinant virus. Our data indicate that the R5-mediated CD4+ lymphocytopenia in the gut is likely independent of HIV-1 genotypes and of the function of vpu at the acute phase of viral infection.     

The impact of highly active antiretroviral therapy by the oral route on the CD8 subset in monkeys infected chronically with SHIV 89.6P

The objective of this study was to assess the impact of highly active antiretroviral therapy (HAART) by an oral route on the peripheral blood CD8 subset in the monkeys infected persistently with a pathogenic strain, SHIV(89.6P). Two rhesus macaques were inoculated intravenously with SHIV(89.6P), then treated with the combination of AZT, 3TC and Lopinavir/Ritonavir (LPV/RTV) as recommended in humans by the oral route with confectionery continued for 28 days. In one of two chronically infected macaques, MM260, the viral load was maintained in the range of 10(4)-10(5) copies/ml before HAART. The plasma viral load and proviral DNA decreased dramatically during the treatment, and cessation of this therapy the viral load rebounded to the pre-treatment level but the proviral DNA rebound was delayed. The other monkey, MM242, had low viral loads (1.2x10(3)-<5x10(2) copies/ml) both before and after HAART. CD4(+) and CD8(+) T cell counts and proviral DNA level were not significantly changed after the treatment. The percentages of CD8(+)CD45RA(-)Ki67(+)cells increased during (MM260) or after (MM242) HAART and the subset was maintained at a high percentage until 18 weeks post HAART in MM242. These findings suggest that this primate model might serve an important role in testing the virological and immunological efficacy of novel therapeutic strategies combined with HAART.     

Quantitative detection of human immunodeficiency virus type 1 (HIV-1) viral load by SYBR green real-time RT-PCR technique in HIV-1 seropositive patients

HIV-1 viral load represents a basic marker for evaluation of the rate and severity of HIV-1 related disease and to monitor the effectiveness of treatment. An SYBR green-based real-time RT-PCR (SYBR green real-time RT-PCR) revealed by Light Cycler technology was evaluated for quantitation of HIV-1 RNA viral load in plasma of HIV-1 seropositive patients. The performance of the SYBR green real-time PCR was assessed on 56 HIV-1 seropositive patients under highly active retroviral therapy (HAART) and 25 blood donors. The results demonstrated that this technique detected 50 HIV-1 RNA copies per millilitre of plasma. Moreover, we compared real-time RT-PCR with the b-DNA technique considered widely a reference technique for HIV-1 RNA viral load measurement. The parallel quantitative analysis of HIV-1 positive samples showed a high correlation (r=0.908) between the two methods. Although b-DNA and the real-time-based method gave similar sensitivity, the assay determined quantitatively HIV-1 RNA copies in 4 out of 16 samples shown as undetectable by b-DNA. The SYBR green real-time RT-PCR represents a good alternative to b-DNA assay in HIV-1 viral load determination especially during the monitoring of HAART treatment.     

Quantitation of HIV-1 RNA levels in plasma and CSF of asymptomatic HIV-1 infected patients from South India using a TaqMan real time PCR assay.

BACKGROUND: Most of the quantitation assays for HIV-1 RNA used currently are designed and optimized for HIV-1 subtype B viruses and hence may not be suitable for India, where the predominant subtype is HIV-1 subtype C. OBJECTIVES: Development and standardization of HIV-1 TaqMan real time PCR assay suitable for measuring plasma and CSF viral RNA levels in HIV subtype C infected individuals. STUDY DESIGN: A TaqMan real time PCR was developed using primers and probes selected in the gag region for detection of Indian HIV-1 subtype C strain. Plasma (n=120) and CSF samples (n=46) obtained from HIV infected subjects were used to evaluate the sensitivity and specificity of the assay. A comparative evaluation was carried out with a commercially available quantitative HIV viral load assay (Roche Amplicor Version 1.5). RESULTS: The TaqMan assay was able to amplify all HIV-1 group M subtypes except subtype E. Viral loads could be estimated in all the plasma (n=120) and 40/46 CSF samples obtained from HIV positive subjects. Sensitivity of this assay was found to be 180 copies/ml. Correlation with the commercially available viral load assay was very good (r=0.885). CONCLUSIONS: A TaqMan real time PCR was standardized for HIV-1 subtype C and it was more sensitive (180 copies/ml) than standard Amplicor monitor assay, Version 1.5 (400 copies/ml).     

Replication,immunogenicity, and protective properties of live-attenuated simian immunodeficiency viruses expressing interleukin-4 or interferon-gamma

Nef deletion mutants of SIV-expressing interleukin-4 (SIV-IL4) or interferon-gamma (SIV-IFN) were constructed to study the effect of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) on viral load, immunogenicity, and protective properties. Four rhesus monkeys were infected with SIV-IL4 and four were infected with SIV-IFN. During the acute phase of infection, the cell-associated viral load, but not the plasma viral RNA load, was approximately 10-fold lower in SIV-IFN-infected macaques than in SIV-IL4-infected rhesus monkeys. The viral load declined to hardly detectable levels 4 months postinfection in all animals. SIV antibody titers and the affinity of these antibodies were higher in SIV-IL4-infected macaques than in SIV-IFN-infected animals, consistent with a stimulation of T helper cell type 2 immune responses by IL-4. At peak viremia, there was a trend to higher interleukin-12 and perforin mRNA levels of the lymph nodes in the SIV-IFN-infected macaques than in the SIV-IL4-infected monkeys. Deletion of the viral IFN gene, but not the viral IL-4 gene, after the development of antiviral immune responses suggests a repressive effect of IFN, but not IL-4, on virus spread in vivo. A trend to higher set point viral RNA levels in SIV-IL4-infected monkeys in comparison to monkeys infected with the parental nef deletion mutant and similar viral RNA levels during the acute phase of infection suggest that IL-4 expression leads to a slight reduction in the control of virus replication by host immune responses. However, SIV-IL4 and SIV-IFN induced protection against a homologous challenge virus. Subsequent challenge with an SIV-HIV-1 hybrid virus (SHIV) also revealed protection in the absence of neutralizing antibodies.