该研究是由来自比尔和梅林达·盖茨基金会通过大挑战全球健康计划的资助。

1.程序的实时qRPA反应的热循环仪<ol><li>创建在热循环仪软件的新协议。 <ol><li>插入预孵育步骤：39℃，1分钟。 </li><li>添加第二个步骤：39℃，20秒，接着是板读。 </li><li>最后，插入一个“GO TO”，重复第二步59次以上。 </li><li>保存的协议。 </li></ol></li><li>在软件的“板块编辑器”选项卡中创建一个新的板块。选择上板孔对应于​​RPA反应的位置（这里，利用井A1，A4-A8，B1和B4-B8）。 注：是否指定井（ 例如，“标准”，“NTC”）的样品类型，使用自定义脚本来完成数据分析并不重要。 <ol><li>对于含有HIV-1 DNA只实验，选择“HEX”荧光所有井。对于含有HIV-1 DNA和内部积极合作实验ntrol，同时选中“HEX”和“FAM”荧光所有井。存盘。 </li></ol></li></ol> 2.准备HIV-1 qRPA实验<ol><li>组装RPA反应在含有指定移液器，移液管尖端，涡流混合器，和微型离心机，作为用于定量PCR指定的前置放大工作区。如RPA可由幅度高达10个数量扩增DNA的单拷贝（数据未示出），处理和处置含有DNA后的扩增产物在一指定的后扩增区管。 <ol><li>防止所有预扩增试剂和扩增后的产品之间的接触。之前和所有实验后喷预放大工作空间和设备，用50％的漂白剂。用纸巾擦去多余的漂白剂。 </li></ol></li><li>购买正向引物序列5&#39;-TGG CAG TAT TCA TTC ACA ATT TTA AAA GAA AAG G-3&#39;和反向引物序列5&#39;-CCC GAA AAT TTT GAA TTT TTG TAA TT牛逼GTT TTT G-3&#39;从商业DNA合成。购买探针序列5&#39;-TGC TAT TAT GTC TAC TAT TCT TTC CCC [SIMA / HEX] GC [THF] C [胸苷BHQ1] GTA CCC CCC AAT CCCç-3&#39;从商业渠道。存储在等份所有引物和探针在4℃以在使用之前为10μM的浓度存在。 注：qRPA法放大了独特的HIV-1的序列。用于概念验证的该试验中，使用由萨顿等人 ，其中包含与靶序列16描述的质粒pHIV-IRES-eYFPΔEnvΔVifΔVpr。对于qRPA实验中，质粒被保存在4℃，在含有在含10mM Tris，0.1毫摩尔EDTA在pH 8.0的缓冲液每μl的1，10，10 2，10 3，和10 4份等分试样，和1纳克/微升的人类基因组DNA的载体（360486）。该载体DNA浓度相当于从用于HIV-1的诊断17商用血清DNA提取试剂盒获得的DNA浓度。这些HIV-1稀释液用作qRPA反应的模板，以建立一个标准曲线。 </li></ol> 3.装配的HIV-1 qRPA标准曲线<ol><li>之前组装qRPA反应，如在步骤2.1.1中所述制备的预放大的工作区。放置在存储96孔冷块在4℃。 </li><li>准备试剂12反应： <ol><li>移动乙酸镁，补液缓冲液，和12 RPA反应粒料到预放大的工作区。 </li><li>解冻的乙酸镁，在室温下再水化缓冲液中。 </li><li>等分32.5微升乙酸镁（每反应2.5微升）到一个离心管中。 </li><li>准备一个13倍母液。加入383.5微升补液缓冲液（每反应29.5微升），以一个单独的离心管中的主结构。添加41.6微升的核酸自由水（每反应3.2微升）的主结构。 VORTEX的主结构。 </li><li>返回镁aceta德和再水化缓冲液储存于-20℃。 </li><li>移动从冰箱到预扩增区域中的引物和探针的等分试样，从而避免过度曝光，以减少光漂白。 </li><li>添加27.3微升各为10μM的正向和反向引物（每个反应的引物2.1微升）到主混合物。 </li><li>加入7.8微升10μMHEX标记的HIV-1 DNA探针（每反应0.6微升）的主结构。 </li><li>返回引物和探针存储。 </li></ol></li><li>匹配在1.2节中描述的板块布局，放置1酶颗粒中的每个最左边管和1酶颗粒在每2低层8孔PCR管带5极右管。 </li><li>仔细增加37.5微升主混合物含有一种酶颗粒每管，采用了新的枪头每个管，轻轻地搅拌预混和球团用刀尖直到沉淀完全溶解。轻轻搅拌以防止泡沫formati，并小心地取出笔尖​​防止反应体积的任何损失。 </li><li>毕竟酶颗粒已经水化与主结构，检索4℃保存96孔冷块。将PCR管带中冷块寒意的主结构。 </li><li>而主混合物被冷却，装入热循环仪软件与协议和板在第1节中所述。 </li><li>切成2片的透明塑料微密封粘合剂为比PCR管稍宽，并检索2扁平PCR管条盖。 </li><li>从存储器中检索模板6等份（含有的每微升的HIV-1的质粒0，1，10 1，10 2，10 3，或10 4个拷贝）。 </li><li>加入10微升每个模板，以指定的模板浓度管。使用新的枪头，每个管，轻轻搅动以尖端混合主结构和模板的解决方案。请务必将模板添加到正确的位置，以米ATCH第1.2节中描述的平板布局。 </li><li>确保PCR管带适配器的离心到位。 </li><li>分配2.5微升乙酸镁进每个管盖，将被放置在含有qRPA反应的管。 </li><li>轻轻地放在盖子上的PCR管，使得它们没有完全密封的，并且可以被去除的顶部。乙酸镁将坚持盖和清晰可见从上面。 </li><li>插入每个PCR管中带材用盖子到PCR管夹持器的每一侧。关闭minifuge的盖，旋乙酸镁出盖子并进入RPA反应，引发RPA反应。离心直至所有气泡被消除，并且所有的液体被收集在每个管（约10秒）的底部。 </li><li>快速去除PCR管条，并将其返回到冷块停止qRPA反应。 </li><li>小心取下盖子，以防止气溶胶的形成和密封每个PCR管带用切个明确的微密封膜。 </li><li>快速步行到热循环仪并加载两个PCR管带成相匹配的板布局（井A1-B8）的位置的热循环仪。关闭热循环仪的盖子，然后单击“开始→运行”，并指定一个文件名实验。 注意：虽然在制造商建议5分钟温育后，搅拌该样品，该步骤不是必需为这个特定测定和可被省略。 </li><li>运行完毕后，选择“设置”，“基线设置”，“没有基线减法”，以显示原始荧光数据。通过选择将数据导出到一个电子表格程序“导出”，“导出所有数据表到Excel中。”A文件增编“定量扩增结果”将创建包含原始的实时荧光数据。 </li></ol> 4.制定一个内部阳性对照<ol><li>选择从一个物种，是不太可能的目标样品中被发现的DNA序列。该序列需要比目标扩增子得较长，以便产生靶序列的是有利的。 注意：对于这个测定法中， 小隐孢子虫 ，肠寄生虫，被选为充当模板用于产生对IPC序列，因为这种微生物是不太可能在血液中被发现并且是可在从另一项目中的实验室。要生成IPC序列，提取和纯化C. DNA 孢子虫卵囊其他地方18所描述。 </li><li>购买前（5&#39;-TGG CAG TAT TCA TTC ACA ATT TTA AAA GAA AAG G / ATC TAA GGA AGG CAG CAG GC-3&#39;）和反向（5&#39;-CCC GAA AAT TTT GAA TTT TTG TAA TTT GTT TTT G / TGC TGG AGT ATT CAA GGC ATA-3&#39;）从商业来源获得的引物。在该试验中所使用的IPC的PCR引物示于图1，并包含一个区域是互补的IPC的模板ðNA（ 例如，微小隐孢子虫 ，紫色在图1）和一个区域是互补的靶生物（ 例如，HIV-1，蓝色于图1）。 </li><li>进行PCR使用引物和IPC模板DNA。 <ol><li>组装根据制造商的说明使用的Phusion高保真DNA聚合酶试剂盒的试剂50μl的PCR反应，但不包括聚合酶。使用2微升DNA模板的Phusion缓冲HF的。 </li><li>添加的Phusion聚合酶到每个反应热启动在98℃，接着60秒，在98℃，随后通过15秒的40个循环后，在98℃，30秒，62℃，和30秒72℃下用在72℃最终延伸5分钟。热循环后，保持在4℃的样品。 </li><li>分析通过凝胶电泳的样品在2％TAE琼脂糖凝胶上，然后提取和使用根据微量协议附带QIAquick凝胶提取试剂盒纯化DNA试剂盒中。 </li></ol></li><li>屏幕IPC候选人为他们的使用qRPA放大能力。 <ol><li>准备qRPA反应，如在第3节所述，使用HIV-1引物，一个FAM标记探针具体到IPC（5&#39;-AGG TAG TGA CAA GAA ATA ACA ATA CAG GAC [FAM] T [THF] T [胸苷BHQ1 ] GGT TTT GTA ATT GGA甲-3&#39;），以及总共0，10，10 2，10 3，10 4或10 5个拷贝每反应各IPC的候选，检验所有浓度一式两份的。 </li><li>选择IPC候选人，放大最一致，并具有最低的极限的检测。 </li></ol></li><li>共扩增的HIV-1和IPC来确定的IPC DNA的最佳浓度。 <ol><li>类似于第3节，结合下面的每50微升反应：29.5微升的补液缓冲区，2.1微升正向引物[10μM]的RPA的，2.1微升RPA的反向引物[10μM]，0.6微升的HIV-1 HEX标记的探针[10μM]，10微升HIV-1的DNA的不同浓度，2.5微升乙酸镁，以及1酶沉淀。代替加入3.2微升不含核酸酶的水作为在步骤3.2.4完成，加入0.6微升的IPC FAM标记的探针[10μM]的，和2.6微升的IPC的DNA。使用IPC浓度是极限- - 的检测限（LOD）时qRPA与IPC DNA的单独（定义为最低浓度，其中荧光信号的产生的量是大于由通过与样本产生的荧光所产生的LOD执行没有目标DNA）。 </li><li>孵育使用1.1​​节中描述的协议的样品。 </li><li>如果IPC不每个样品中扩增，考虑重复实验幅度更高的IPC浓度一个数量级。 IPC DNA的HIV-1检测的最佳浓度为10000拷贝/微升。虽然样本被认为是有效的，如果有任何IPC或HIV-1 DNA扩增，理想的IPC具有检测扩增每一个反应。 </li></ol></li></ol> 5.建立来自多个实验标准曲线<ol><li>确保数据在第3.13节描述的每个实验已出口到电子表格程序。 </li><li>打开并运行脚本“JoVE_qRPA_standard_curve.m”。所有的输入会自动提示，在命令窗口。被启动的脚本后，用户被自动提示指定“的数据文件数”用于构建标准曲线。 </li><li>在命令窗口中，键入要使用的文件的数量来构建标准曲线，然后按回车。 </li><li>在命令窗口中键入的样本数和重复在每个训练文件数（按下每个条目后进入）。 注：在1.2节中描述的板布局，有6个样品不同浓度和2次重复每个样品）。 </li><li>请在命令窗口中最低的DN用于构建标准曲线（以log10拷贝），然后按回车浓度（在1.2节中描述的板块布局，最低模板浓度为1 log10拷贝）。 </li><li>在命令窗口中输入每个标准间的浓度差（以log10拷贝），然后按回车键（在1.2节中描述的板块布局，集中时间间隔为1 log10拷贝）。 </li><li>提示后，请在命令窗口中的“斜率阈值”，然后按Enter。 </li><li>在命令窗口中，键入“号（Z）的背景正阈值以上的标准偏差”，然后按回车键。典型值z范围从1至5。 </li><li>指定使用热循环仪（&#39;1&#39;）中的数据是否被收集，* .TIFF显微镜图像（&#39;2&#39;），或* .JPG显微镜图像（&#39;3&#39;），通过输入数字“1”，“2”，或&#39;3&#39;和对ressing进入。 </li><li>选择设置新的门槛IPC或键入分别为&#39;Y&#39;或&#39;N&#39;，出现提示时使用的阈值的默认值。 </li><li>接下来，选择每个用于构建标准曲线的电子表格文件。 注：随后，脚本会自动导入HEX和FAM荧光数据;确定各反应是否是有效的（ 即，无论是荧光信号超过阈值，HEX或FAM通道）;确定第r 2系数的指数，线性和二阶多项式拟合;暗算“log10拷贝与循环门槛”，每用于构建标准曲线样品;并创建包含基本变量来重建标准曲线进行验证实验，而不需要用户重新输入所有输入参数的再一个电子表格文件。 </li></ol> 6.试验验证和未知样品使用的量化标准曲线<ol><li>使用的脚本“JoVE_qRPA_validation_and_quantification.m”通过使用样品与已知浓度来估计测定的精度和准确度，或用它来量化样品与未知浓度。 注：因为之前发表的报告显示，指数拟合得到最好的R平方系数18，这个脚本利用一个指数拟合的标准曲线。如果不同类型的合适的是理想的，该脚本可以被相应地修改。 <ol><li>打开并运行脚本“JoVE_qRPA_validation_and_quantification.m”。启动脚本后，该用户将自动提示输入所有输入到命令窗口。 </li><li>输入“1”用标准曲线与已知样品的浓度来验证试验或输入“2”量化未知样品。 </li><li>当系统提示，要么选择一个保存的标准曲线或进入日建一个新的E资料是在命令窗口中自动搜罗（即所需“JoVE_qRPA_standard_curve.m”剧本从第5相同的信息）。 </li><li>类型的实验数量（ 即电子表格文件）来分析进行验证/定量。 </li></ol></li></ol> 7.筹备数据收集使用荧光显微镜和加热芯片<ol><li>确保荧光显微镜有一个阶段，加热器和1通道，高精度，高稳定性温度控制器到位。 </li><li>确保荧光显微镜有一个过滤器立方体激发并从每个荧光收集荧光。激发和收集通过GFP过滤器（激发BP四十分之四百七十○纳米，发射BP五十〇分之五百二十○纳米）IPC DNA扩增过程中产生的FAM荧光。激发和收集通过HEX过滤器（BP激发波长530/30，排放BP40分之575nm）的HIV-1 DNA扩增过程中产生的HEX荧光。 </li><li>使用显微镜脚本编辑软件来创建一个自动算法来复制的热循环仪的数据收集。 <ol><li>第一插入一个“设置”步骤以关闭快门。下一步添加一个“曝光”一步曝光设置为60秒。将“捕捉”执行60秒的延迟，它实现了1分钟前的潜伏期。添加一个“设置”步骤的工作组更改为GFP过滤器。插入另一张“暴露”的步骤来调整曝光，以200毫秒。使用GFP或HEX滤波器立方体所有曝光将被设置为200毫秒。 </li><li>之后，“曝光”的步骤，添加一个“快照”，指定该图像将采取相机。使用另一个“设置”的步骤，关闭快门和“保存图像”的步骤将图像保存到一个用户定义的临时文件夹。 </li><li>使用另一个“设置”的步骤和TH接下来切换到HEX过滤立方体恩添加“曝光”在200毫秒，一个“快”和“保存图像”的步骤。 </li><li>重复此过程59次20秒而不是60（靠近快门的初始延迟，等待20秒，切换到GFP滤块，设置曝光为200毫秒，扣，关闭快门，保存，切换到HEX滤块，设置曝光至200毫秒，SNAP）。 </li></ol></li><li>创建一个芯片将举行qRPA反应。 <ol><li>为使用显微镜的实验中，使用文件JoVE_qRPA_base.ai于使用激光切割器设定为100％的功率，10％的速度从1/8“厚的黑色丙烯酸树脂的片材切割为40×15毫米矩形基。 </li><li>使用文件JoVE_qRPA_well.ai切割反应以及由一个10×10平方毫米的具有从1.5毫米厚的透明的丙烯酸片材一个5mm直径的圆形孔切割。 </li><li>连上三个井用强力胶凝胶一个基地。 </li><li>干燥过夜。 </li></ol></li></ol> 8.数据收集和ANALYSIS使用荧光显微镜<ol><li>通过装载自动数据收集脚本JoVE_AxioVision_Script.ziscript准备显微镜进行数据收集。 <ol><li>设置阶段加热器至48℃和预热上段加热器的反应芯片为约20分钟。 48℃的温度设定保持39°C的反应以及温度（数据未显示）。 </li><li>使用10X，0.45 NA物镜，着​​眼于反应很好地与代替GFP过滤器的内边缘的顶部。丙烯酸类的边缘激光切割后自身荧光，并且可以很容易地可视化。对焦后，不调整显微镜阶段的高度，直到所有的数据收集。 </li></ol></li><li>组装qRPA预混在指定的前置放大工作区，如步骤4.5.1描述。对于每个样本，混合酶颗粒，主控组合，并在离心管中HIV-1 DNA模板。加入2.5微升的醋酸镁至第一reaction和简要旋涡。 </li><li>迅速输送含有qRPA样品荧光显微镜的离心管中。 <ol><li>认真吸取30微升的RPA反应到反应良好，没有产生气泡。放置一滴的PCR级矿物油在RPA反应以防止蒸发。 </li><li>定位以及直接的显微镜物镜下，注意图像只有中央的很好，没有任何自动荧光亚克力边缘。井被定位后，运行自动化的脚本7.脚本中使用FAM过滤立方体和使用HEX滤块每20秒1 JPEG图像生成一个JPEG图像。 </li></ol></li><li>剧本完成后，运行其他样品之前，这些转移出来的图像临时存储文件夹中。 <ol><li>每个荧光基团（ 即 “十六进制”和“FAM”）1：创建2个文件夹。存储在同一个父文件夹这两个文件夹。在每一个荧光文件夹中创建标记存在于样品（ 例如，0，10，等等 ）中的DNA拷贝数的文件夹。 </li><li>转移的前缀“HEX”所有文件到相应的子文件夹中的“HEX”文件夹中。转移在“FAM”文件夹中的前缀“GFP”进入相应的子文件夹中的所有文件。 </li></ol></li><li>对于qRPA反应以0，10，10 2，10 3，10 4，和10 5的HIV-1 DNA拷贝重复部分8.2-8.4。 </li><li>收集在一个实验中所有样品qRPA数据后，加载脚本“JoVE_real_time_intensity_to_excel.m。”当脚本提示时，选择含有2荧光的文件夹，这反过来又包含子文件夹中的每个浓度的图像的父文件夹。 注：该脚本将自动生成在其中HEX荧光数据将被保存在一个表南的父目录中的电子表格文件主编“HEX”，和FAM荧光数据将被保存在一个名为“FAM”表。在每个片材中，循环数被列在B列，和用于增加模板的浓度的实时荧光数据中列C，D 等中给出。每个实时荧光数据是在该时间点拍摄的图像的平均荧光强度。 </li><li>使用默认的散点图功能的电子表格程序绘制单元格B2：在“HEX”和“FAM”片H61形象化实时荧光并产生图类似于图2A，2B，3A和3B。 注：在步骤8.6中产生的电子表格，也可以在脚本“JoVE_qRPA_standard_curve.m”和“JoVE_qRPA_validation_and_quantification.m”使用。 </li></ol>

<ol>
	<li>Yoon, J. -. Y., Kim, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lab-on-a-Chip+Pathogen+Sensors+for+Food+Safety.">Lab-on-a-Chip Pathogen Sensors for Food Safety.</a> Sensors. 12 (8), 10713-10741 (2012).</li><li>Quintero-Betancourt, W., Peele, E. R., Rose, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryptosporidium+parvum+and+Cyclospora+cayetanensis:+A+review+of+laboratory+methods+for+detection+of+these+waterborne+parasites.">Cryptosporidium parvum and Cyclospora cayetanensis: A review of laboratory methods for detection of these waterborne parasites.</a> Journal of Microbiological Methods. 49 (3), 209-224 (2002).</li><li>Sedlak, R. H., Jerome, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viral+diagnostics+in+the+era+of+digital+polymerase+chain+reaction.">Viral diagnostics in the era of digital polymerase chain reaction.</a> Diagnostic Microbiology and Infectious Disease. 75 (1), 1-4 (2013).</li><li>Asiello, P. J., Baeumner, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniaturized+isothermal+nucleic+acid+amplification,+a+review.">Miniaturized isothermal nucleic acid amplification, a review.</a> Lab on a Chip. 11 (8), 1420-1430 (2011).</li><li>Piepenburg, O., Williams, C. H., Stemple, D. L., Armes, N. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+detection+using+recombination+proteins.">DNA detection using recombination proteins.</a> PLoS Biology. 4 (7), 1115-1121 (2006).</li><li>Kr&#245;lov, K., Frolova, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+and+Rapid+Detection+of+Chlamydia+trachomatis+by+Recombinase+Polymerase+Amplification+Directly+from+Urine+Samples.">Sensitive and Rapid Detection of Chlamydia trachomatis by Recombinase Polymerase Amplification Directly from Urine Samples.</a> The Journal of Molecular Diagnostics JMD. 16 (1), 127-135 (2014).</li><li>Santiago-Felipe, S., Tortajada-Genaro, L. a., Puchades, R., Maquieira, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recombinase+polymerase+and+enzyme-linked+immunosorbent+assay+as+a+DNA+amplification-detection+strategy+for+food+analysis.">Recombinase polymerase and enzyme-linked immunosorbent assay as a DNA amplification-detection strategy for food analysis.</a> Analytica Chimica Acta. 811 (1), 81-87 (2014).</li><li>Kersting, S., Rausch, V., Bier, F. F., von Nickisch-Rosenegk, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+detection+of+Plasmodium+falciparum+with+isothermal+recombinase+polymerase+amplification+and+lateral+flow+analysis.">Rapid detection of Plasmodium falciparum with isothermal recombinase polymerase amplification and lateral flow analysis.</a> Malaria Journal. 13 (1), 99 (2014).</li><li>Crannell, Z. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleic+Acid+test+to+diagnose+cryptosporidiosis:+lab+assessment+in+animal+and+patient+specimens.">Nucleic Acid test to diagnose cryptosporidiosis: lab assessment in animal and patient specimens.</a> Analytical Chemistry. 86 (5), 2565-2571 (2014).</li><li>Rohrman, B. A., Richards-Kortum, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+paper+and+plastic+device+for+performing+recombinase+polymerase+amplification+of+HIV+DNA.">A paper and plastic device for performing recombinase polymerase amplification of HIV DNA.</a> Lab on a Chip. 12 (17), 3082 (2012).</li><li>Loo, J. F. C., Lau, P. M., Ho, H. P., Kong, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+aptamer-based+bio-barcode+assay+with+isothermal+recombinase+polymerase+amplification+for+cytochrome-c+detection+and+anti-cancer+drug+screening.">An aptamer-based bio-barcode assay with isothermal recombinase polymerase amplification for cytochrome-c detection and anti-cancer drug screening.</a> Talanta. 115 (1), 159-165 (2013).</li><li>Euler, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+panel+of+recombinase+polymerase+amplification+assays+for+detection+of+biothreat+agents.">Development of a panel of recombinase polymerase amplification assays for detection of biothreat agents.</a> Journal of Clinical Microbiology. 51 (4), 1110-1117 (2013).</li><li>Abd El Wahed, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+portable+reverse+transcription+recombinase+polymerase+amplification+assay+for+rapid+detection+of+foot-and-mouth+disease+virus.">A portable reverse transcription recombinase polymerase amplification assay for rapid detection of foot-and-mouth disease virus.</a> PloS One. 8 (8), e71642 (2013).</li><li>Escadafal, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Molecular+Assays+for+the+Detection+of+Yellow+Fever+Virus+in+Low-Resource+Settings.">Rapid Molecular Assays for the Detection of Yellow Fever Virus in Low-Resource Settings.</a> PLoS Neglected Tropical Diseases. 8 (3), e2730 (2014).</li><li>Hutson, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T.+gondii+RP+Promoters+&amp;+Knockdown+Reveal+Molecular+Pathways+Associated+with+Proliferation+and+Cell-Cycle+Arrest.">T. gondii RP Promoters &amp; Knockdown Reveal Molecular Pathways Associated with Proliferation and Cell-Cycle Arrest.</a> PLoS ONE. 5 (11), 15 (2010).</li><li>Segall, H. I., Yoo, E., Sutton, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+detection+of+artificial+replication-competent+lentivirus+of+altered+host+range.">Characterization and detection of artificial replication-competent lentivirus of altered host range.</a> Molecular Therapy. 8 (1), 118-129 (2003).</li><li>Crannell, Z. A., Rohrman, B. A., Richards-Kortum, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+HIV-1+DNA+using+Real-Time+Recombinase+Polymerase+Amplification.">Quantification of HIV-1 DNA using Real-Time Recombinase Polymerase Amplification.</a> Analytical Chemistry. 86 (12), (2014).</li><li>Sollis, K. a., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+review+of+the+performance+of+HIV+viral+load+technologies+on+plasma+samples.">Systematic review of the performance of HIV viral load technologies on plasma samples.</a> PloS one. 9 (2), e85869 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. , 1-166 (2011).</li></ol>

The authors declare they have no competing financial interests.

为了获得使用MATLAB算法有意义的量化数据，系统提示时，用户必须选择合适的输入值。开始在第5和第6的每个脚本之后，所有的输入变量自动征求在命令窗口中，并自动生成输出。在第5.7节中提示用户选择斜率阈值。的斜率阈值影响契合的相关系数（R 2）的平方。当使用从热循环仪导出原始荧光数据，在2.0和5.0的值趋向于产生高R 2系数。在第5.8节，用户必须指定背景以上的标准偏?...

定量核酸扩增是用于检测环境，食源性和水生病原体，以及用于临床诊断的一项重要技术。实时定量聚合酶链反应（qPCR的）可以灵敏，特异和定量检测的核酸， 例如，HIV-1的病毒载量检测，检测的细菌病原体，并筛选许多其他生物体1的金标准方法- 3。在实时定量PCR，引物扩增在周期病原体的DNA和荧光信号被产生成比例的扩增的DNA的样​​品，在每个循环中的量。将含有未知浓度的病原体的DNA的样品可以使用涉及标准样品的初始DNA浓度和在该荧光信号达到一定的阈值的时间（ 即，循环阈值，或（C T））的标准曲线进行定量。 4。这些平台通常提供结果更快和扩增核酸在一个较低的，单一的温度，其可以实现与更便宜，更简单的设备。 RPA，其用于护理点的应用特别有吸引力的，放大的DNA在几分钟内，需要低放大温度（37℃），并且在杂质5,6存在下保持有效。 RPA试验已经开发了用于范围广泛的应用，包括食品分析，病原体检测，癌症药物筛选，并检测生物威胁因子7 - 12。然而，使用的RPA的用于核酸定量一直局限于13,14。 在以往的工作，这是笑WN的实时定量RPA（qRPA）是可行的15。这里，更详细的协议提供了一种用于使用实时定量RPA量化使用标准曲线中，一种方法使用qPCR即类似于量化未知样品。本协议描述了如何执行在热循环的RPA反应检测HIV-1 DNA作为概念证明的，以及如何开发一个内部阳性对照（IPC），以保证系统正常运行。使用热循环仪或显微镜和数据分析使用训练数据构建的标准曲线数据收集也详细叙述。最后，该方法用于定量用标准曲线与自定义脚本未知样品被证实。此qRPA技术使具有未知浓度的样品进行定量，并具有比传统的实时定量PCR的许多优点。

<table border="0" cellpadding="0" cellspacing="0" width="1426">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:443px;">qRPA Assay</td>
			<td style="width:199px;"></td>
			<td style="width:195px;"></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Supply</td>
			<td>Vendor</td>
			<td>Part number</td>
			<td style="width:589px;">Comments/Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HIV-1 forward primer</td>
			<td>Integrated DNA Technologies</td>
			<td>custom DNA oligos</td>
			<td style="width:589px;">5&#8217;-TGG CAG TAT TCA TTC ACA ATT TTA AAA GAA AAG G-3&#8217;&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HIV-1 reverse primer</td>
			<td>Integrated DNA Technologies</td>
			<td>custom DNA oligos</td>
			<td style="width:589px;">5&#8217;-CCC GAA AAT TTT GAA TTT TTG TAA TTT GTT TTT G-3&#8217;&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">HIV-1 probe</td>
			<td>BioSearch Technologies&#160;</td>
			<td>custom DNA oligos</td>
			<td style="width:589px;">5&#8217;- TGC TAT TAT GTC TAC TAT TCT TTC CCC [SIMA/HEX] GC [THF] C [dT-BHQ1] GTA CCC CCC AAT CCC C -3&#8217;&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">IPC probe</td>
			<td>BioSearch Technologies&#160;</td>
			<td>custom DNA oligos</td>
			<td style="width:589px;">5&#8217;-AGG TAG TGA CAA GAA ATA ACA ATA CAG GAC [FAM] T [THF] T [dT-BHQ1] GGT TTT GTA ATT GGA A -3&#8217;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">RPA exo reagents (pellets, rehydration buffer, magnesium acetate</td>
			<td>TwistDx</td>
			<td>TwistAmp exo</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR tube strips</td>
			<td>BioRad</td>
			<td>TLS0801</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR flat cap tube strips</td>
			<td>BioRad</td>
			<td>TCS0803</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Micro-seal adhesive</td>
			<td>BioRad</td>
			<td>558/MJ&#160;</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;">HIV-1 target (pHIV-IRES- eYFP&#916;Env&#916;Vif&#916;Vpr)</td>
			<td></td>
			<td></td>
			<td style="width:589px;">custom plasmid, see: Segall, H. I., Yoo, E. &#38; Sutton, R. E. Characterization and detection of artificial replication-competent lentivirus of altered host range. Molecular Therapy 8, 118&#8211;129, doi:10.1016/S1525-0016(03)00134-5 (2003).</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Human male genomic DNA</td>
			<td>Applied Biosystems</td>
			<td>360486</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">96 well cold-block</td>
			<td>Cole Parmer</td>
			<td>EW-36700-48</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Thermal cycler</td>
			<td>BioRad</td>
			<td>CFX96</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MiniFuge</td>
			<td>VWR</td>
			<td>93000-196</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Vortex</td>
			<td>VWR</td>
			<td>58816-121</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tris buffer 1.0 M, pH 8.0</td>
			<td>EMD Millipore</td>
			<td>648314</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EDTA 0.5 M, pH 8.0</td>
			<td>Promega</td>
			<td>V4321</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Nuclease free water</td>
			<td>Ambion</td>
			<td>AM9937</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">IPC Development</td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Supply</td>
			<td>Vendor</td>
			<td>Part number</td>
			<td style="width:589px;">Comments/Description</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;">Cryptosporidium parvum IPC template</td>
			<td>Waterborne Inc</td>
			<td>P102C</td>
			<td style="width:589px;">It is also possible to order a double stranded synthetic target from IDT if the user is unequipped to work with C. parvum (a BSL-2 infectious agent). PCR and RPA primers for C. parvum were designed using GenBank accession number AF115377.1</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR long forward primer</td>
			<td>Integrated DNA Technologies</td>
			<td>custom DNA oligos</td>
			<td>5&#8217;-TGG CAG TAT TCA TTC ACA ATT TTA AAA GAA AAG G/ ATC TAA GGA AGG CAG CAG GC-3&#8217;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR long reverse primer</td>
			<td>Integrated DNA Technologies</td>
			<td>custom DNA oligos</td>
			<td>5&#8217;- CCC GAA AAT TTT GAA TTT TTG TAA TTT GTT TTT G/ TGC TGG AGT ATT CAA GGC ATA -3&#8217;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Phusion High-Fidelty DNA Polymerase</td>
			<td>New England Biolabs</td>
			<td>M0530S</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Qiaquick Gel Extraction Kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TAE 10X buffer</td>
			<td>EMD Millipore</td>
			<td>574797</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Agarose</td>
			<td>Sigma Aldrich</td>
			<td>A9539</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microscope Experiments</td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Supply</td>
			<td>Vendor</td>
			<td>Part number</td>
			<td style="width:589px;">Comments/Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Upright fluorescence microscope</td>
			<td>Zeiss</td>
			<td>Zeiss Imager.J1</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Stage heater</td>
			<td>Bioscience Tools</td>
			<td>TC-GSH</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1-Channel Precision High Stability Temperature Controller</td>
			<td>Bioscience Tools</td>
			<td>TC-1100S</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">FAM/GFP filter cube</td>
			<td>Zeiss</td>
			<td>filter set 38 (000000-1031-346)</td>
			<td style="width:589px;">excitation BP 470/40 nm, emission BP 520/50 nm</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HEX filter cube</td>
			<td>Chroma</td>
			<td>49014</td>
			<td style="width:589px;">excitation BP 530/30 nm, emission BP 575/40 nm</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laser cutter</td>
			<td>Engraver&#39;s Network</td>
			<td>VLS3.60</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1/8&#34; black acrylic</td>
			<td>McMaster Carr</td>
			<td>8505K113</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1.5 mm clear acrylic</td>
			<td>McMaster Carr</td>
			<td>PD-72268940&#160;</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Super glue</td>
			<td>Office Depot</td>
			<td>Duro super glue&#160;</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PCR grade mineral oil</td>
			<td>Sigma Aldrich</td>
			<td>M8662-5VL</td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Data Analysis</td>
			<td></td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Software</td>
			<td>Vendor</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microsoft Excel</td>
			<td>Microsoft</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MATLAB</td>
			<td>MATLAB</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MATLAB script: &#34;JoVE_qRPA_standard_curve.m&#8221;</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MATLAB script: &#34;JoVE_qRPA_validation_and_quantification.m&#8221;</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MATLAB script: &#34;JoVE_real_time_intensity_to_excel.m&#8221;</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Adobe Illustrator</td>
			<td>Adobe</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">JoVE_qRPA_well.ai</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">JoVE_qRPA_base.ai</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">AxioVision software</td>
			<td>Zeiss</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">JoVE_AxioVision_Script.ziscript</td>
			<td>Included in SI</td>
			<td></td>
			<td style="width:589px;"></td>
		</tr>
	</tbody>
</table>

development of a quantitative recombinase polymerase amplification assay with an internal positive control

It was recently demonstrated that recombinase polymerase amplification (RPA), an isothermal amplification platform for pathogen detection, may be used to quantify DNA sample concentration using a standard curve. In this manuscript, a detailed protocol for developing and implementing a real-time quantitative recombinase polymerase amplification assay (qRPA assay) is provided. Using HIV-1 DNA quantification as an example, the assembly of real-time RPA reactions, the design of an internal positive control (IPC) sequence, and co-amplification of the IPC and target of interest are all described. Instructions and data processing scripts for the construction of a standard curve using data from multiple experiments are provided, which may be used to predict the concentration of unknown samples or assess the performance of the assay. Finally, an alternative method for collecting real-time fluorescence data with a microscope and a stage heater as a step towards developing a point-of-care qRPA assay is described. The protocol and scripts provided may be used for the development of a qRPA assay for any DNA target of interest.

选择一个序列作为IPC在qRPA实验目标之前（HIV-1）的DNA，内部阳性对照（IPC）的候选人中产生和筛选它们放大的qRPA反应无HIV-1 DNA存在的能力。 IPC考生比目标（HIV-1）的DNA，以防止出竞争的HIV-1扩增子形成IPC形成更长的时间。 如图2A所示 ，两个C的代孢子虫 IPC候选人是由使 ​​用凝胶电泳415和435 bp的条带的存在验证。在qRPA反应，较短的IPC候选呈现小的扩增（ 图2B），<...

Watch this Scientific Journal Video about Development of a Quantitative Recombinase Polymerase Amplification Assay with an Internal Positive Control at JoVE.com

Development of a Quantitative Recombinase Polymerase Amplification Assay with an Internal Positive Control

Provided is a protocol for developing a real-time recombinase polymerase amplification assay to quantify initial concentration of DNA samples using either a thermal cycler or a microscope and stage heater. Also described is the development of an internal positive control. Scripts are provided for processing raw real-time fluorescence data.

一个定量聚合酶重组酶扩增法的发展与内部阳性对照

It was recently demonstrated that recombinase polymerase amplification (RPA), an isothermal amplification platform for pathogen detection, may be used to ...

development-quantitative-recombinase-polymerase-amplification-assay

Research

JoVE Journal

Biology

13.4K 次观看.  Rice University. Provided is a protocol for developing a real-time recombinase polymerase amplification assay to quantify initial concentration of DNA samples using either a thermal cycler or a microscope and stage heater. Also described is the development of an internal positive control. Scripts are provided for processing raw real-time fluorescence data.

视频: Development of a Quantitative Recombinase Polymerase Amplification Assay with an Internal Positive Control

Principles of Site-Specific Recombinase (SSR) Technology

Site-specific recombinase (SSR) technology allows the manipulation of gene structure to explore gene function and has become an integral tool of molecular biology. Site-specific recombinases are proteins that bind to distinct DNA target sequences. The Cre/lox system was first described in bacteriophages during the 1980's. Cre recombinase is a Type I topoisomerase that catalyzes site-specific recombination of DNA between two loxP (locus of X-over P1) sites. The Cre/lox system does not require any cofactors. LoxP sequences contain distinct binding sites for Cre recombinases that surround a directional core sequence where recombination and rearrangement takes place. When cells contain loxP sites and express the Cre recombinase, a recombination event occurs. Double-stranded DNA is cut at both loxP sites by the Cre recombinase, rearranged, and ligated ("scissors and glue"). Products of the recombination event depend on the relative orientation of the asymmetric sequences.
SSR technology is frequently used as a tool to explore gene function. Here the gene of interest is flanked with Cre target sites loxP ("floxed"). Animals are then crossed with animals expressing the Cre recombinase under the control of a tissue-specific promoter. In tissues that express the Cre recombinase it binds to target sequences and excises the floxed gene. Controlled gene deletion allows the investigation of gene function in specific tissues and at distinct time points. Analysis of gene function employing SSR technology --- conditional mutagenesis -- has significant advantages over traditional knock-outs where gene deletion is frequently lethal.

Principles of Site-Specific Recombinase SSR Technology

The advent of site-specific recombinase (SSR) technology and the Cre/lox system has led to numerous advances in molecular biology, and has proven itself as a valuable tool for assessing gene function in transgenic animals. This interview discusses the mechanism of site specific recombination by Cyclization recombinase (Cre) and how the use of this enzyme has led to the development of conditional mutagenesis, which has significant advantages over traditional knock out strategies.

特定地点的重组酶（SSR）技术的原则

Site-specific recombinase (SSR) technology allows the manipulation of gene structure to explore gene function and has become an integral tool of molecular ...

科研

生物学

Interview: HIV-1 Proviral DNA Excision Using an Evolved Recombinase

HIV-1 integrates into the host chromosome of infected cells and persists as a provirus flanked by long terminal repeats. Current treatment strategies primarily target virus enzymes or virus-cell fusion, suppressing the viral life cycle without eradicating the infection. Since the integrated provirus is not targeted by these approaches, new resistant strains of HIV-1 may emerge. Here, we report that the engineered recombinase Tre (see Molecular evolution of the Tre recombinase , Buchholz, F., Max Planck Institute for Cell Biology and Genetics, Dresden) efficiently excises integrated HIV-1 proviral DNA from the genome of infected cells. We produced loxLTR containing viral pseudotypes and infected HeLa cells to examine whether Tre recombinase can excise the provirus from the genome of HIV-1 infected human cells. A virus particle-releasing cell line was cloned and transfected with a plasmid expressing Tre or with a parental control vector. Recombinase activity and virus production were monitored. All assays demonstrated the efficient deletion of the provirus from infected cells without visible cytotoxic effects. These results serve as proof of principle that it is possible to evolve a recombinase to specifically target an HIV-1 LTR and that this recombinase is capable of excising the HIV-1 provirus from the genome of HIV-1-infected human cells.
Before an engineered recombinase could enter the therapeutic arena, however, significant obstacles need to be overcome. Among the most critical issues, that we face, are an efficient and safe delivery to targeted cells and the absence of side effects.

Current HIV-1 strategies act to suppress the viral life cycle but do not effectively eradicate infection. Here, we demonstrate that an engineered recombinase can efficiently excise integrated HIV-1 proviral DNA from the genome of infected cells.

专访：HIV - 1前病毒DNA切除使用一个演进的重组酶

HIV-1 integrates into the host chromosome of infected cells and persists as a provirus flanked by long terminal repeats. Current treatment strategies ...

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

一个神经元和星形胶质细胞共培养检测神经毒性的高含量分析

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

A Quantitative Assay for Insulin-expressing Colony-forming Progenitors

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the analysis of the single cell. Analyses of single progenitors are of critical importance because they provide definitive ways to unequivocally demonstrate the lineage potential of individual progenitors. Although methods have been devised to generate "pancreatospheres" in suspension culture from single cells, several limitations exist. First, it is time-consuming to perform single cell deposition for a large number of cells, which in turn commands large volumes of culture media and space. Second, numeration of the resulting pancreatospheres is labor-intensive, especially when the frequency of the pancreatosphere-initiating progenitors is low. Third, the pancreatosphere assay is not an efficient method to allow both the proliferation and differentiation of pancreatic progenitors in the same culture well, restricting the usefulness of the assay.
To overcome these limitations, a semi-solid media based colony assay for pancreatic progenitors has been developed and is presented in this report. This method takes advantage of an existing concept from the hematopoietic colony assay, in which methylcellulose is used to provide viscosity to the media, allowing the progenitor cells to stay in three-dimensional space as they undergo proliferation as well as differentiation. To enrich insulin-expressing colony-forming progenitors from a heterogeneous population, we utilized cells that express neurogenin (Ngn) 3, a pancreatic endocrine progenitor cell marker. Murine embryonic stem (ES) cell-derived Ngn3 expressing cells tagged with the enhanced green fluorescent protein reporter were sorted and as many as 25,000 cells per well were plated into low-attachment 24-well culture dishes. Each well contained 500 &mu;L of semi-solid media with the following major components: methylcellulose, Matrigel, nicotinamide, exendin-4, activin &beta;B, and conditioned media collected from murine ES cell-derived pancreatic-like cells. After 8 to 12 days of culture, insulin-expressing colonies with distinctive morphology were formed and could be further analyzed for pancreatic gene expression using quantitative RT-PCR and immunoflourescent staining to determine the lineage composition of each colony.
In summary, our colony assay allows easy detection and quantification of functional progenitors within a heterogeneous population of cells. In addition, the semi-solid media format allows uniform presentation of extracellular matrix components and growth factors to cells, enabling progenitors to proliferate and differentiate in vitro. This colony assay provides unique opportunities for mechanistic studies of pancreatic progenitor cells at the single cell level.

A three-dimensional clonogenic assay that allows pancreatic-like progenitors to differentiate into insulin-expressing colonies is described. This method takes advantage of semi-solid media containing methylcellulose, Matrigel and growth factors, in which single progenitors proliferate and differentiate in vitro, permitting quantification of the number of functional progenitors in a population.

一个定量测定胰岛素表达细胞集落形成先觉

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the ...

A Semi-quantitative Approach to Assess Biofilm Formation Using Wrinkled Colony Development

Biofilms, or surface-attached communities of cells encapsulated in an extracellular matrix, represent a common lifestyle for many bacteria. Within a biofilm, bacterial cells often exhibit altered physiology, including enhanced resistance to antibiotics and other environmental stresses 1. Additionally, biofilms can play important roles in host-microbe interactions. Biofilms develop when bacteria transition from individual, planktonic cells to form complex, multi-cellular communities 2. In the laboratory, biofilms are studied by assessing the development of specific biofilm phenotypes. A common biofilm phenotype involves the formation of wrinkled or rugose bacterial colonies on solid agar media 3. Wrinkled colony formation provides a particularly simple and useful means to identify and characterize bacterial strains exhibiting altered biofilm phenotypes, and to investigate environmental conditions that impact biofilm formation. Wrinkled colony formation serves as an indicator of biofilm formation in a variety of bacteria, including both Gram-positive bacteria, such as Bacillus subtilis 4, and Gram-negative bacteria, such as Vibrio cholerae 5, Vibrio parahaemolyticus 6, Pseudomonas aeruginosa 7, and Vibrio fischeri 8.
The marine bacterium V. fischeri has become a model for biofilm formation due to the critical role of biofilms during host colonization: biofilms produced by V. fischeri promote its colonization of the Hawaiian bobtail squid Euprymna scolopes 8-10. Importantly, biofilm phenotypes observed in vitro correlate with the ability of V. fischeri cells to effectively colonize host animals: strains impaired for biofilm formation in vitro possess a colonization defect 9,11, while strains exhibiting increased biofilm phenotypes are enhanced for colonization 8,12. V. fischeri therefore provides a simple model system to assess the mechanisms by which bacteria regulate biofilm formation and how biofilms impact host colonization.
In this report, we describe a semi-quantitative method to assess biofilm formation using V. fischeri as a model system. This method involves the careful spotting of bacterial cultures at defined concentrations and volumes onto solid agar media; a spotted culture is synonymous to a single bacterial colony. This 'spotted culture' technique can be utilized to compare gross biofilm phenotypes at single, specified time-points (end-point assays), or to identify and characterize subtle biofilm phenotypes through time-course assays of biofilm development and measurements of the colony diameter, which is influenced by biofilm formation. Thus, this technique provides a semi-quantitative analysis of biofilm formation, permitting evaluation of the timing and patterning of wrinkled colony development and the relative size of the developing structure, characteristics that extend beyond the simple overall morphology.

We provide a simple, semi-quantitative method to investigate biofilm formation in vitro. This method takes advantage of the Zeiss stemi 2000-C Dissecting Microscope (with camera attachment) to monitor both the timing and pattern of biofilm formation, as assessed by the development of wrinkled colonies.

一个半定量的方法来评估生物膜形成皱殖民地的发展

Biofilms, or surface-attached communities of cells encapsulated in an extracellular matrix, represent a common lifestyle for many bacteria. Within a ...

Conversion of a Capture ELISA to a Luminex xMAP Assay using a Multiplex Antibody Screening Method

The enzyme-linked immunosorbent assay (ELISA) has long been the primary tool for detection of analytes of interest in biological samples for both life science research and clinical diagnostics. However, ELISA has limitations. It is typically performed in a 96-well microplate, and the wells are coated with capture antibody, requiring a relatively large amount of sample to capture an antigen of interest . The large surface area of the wells and the hydrophobic binding of capture antibody can also lead to non-specific binding and increased background. Additionally, most ELISAs rely upon enzyme-mediated amplification of signal in order to achieve reasonable sensitivity. Such amplification is not always linear and can thus skew results.
In the past 15 years, a new technology has emerged that offers the benefits of the ELISA, but also enables higher throughput, increased flexibility, reduced sample volume, and lower cost, with a similar workflow 1, 2. Luminex xMAP Technology is a microsphere (bead) array platform enabling both monoplex and multiplex assays that can be applied to both protein and nucleic acid applications 3-5. The beads have the capture antibody covalently immobilized on a smaller surface area, requiring less capture antibody and smaller sample volumes, compared to ELISA, and non-specific binding is significantly reduced. Smaller sample volumes are important when working with limiting samples such as cerebrospinal fluid, synovial fluid, etc. 6. Multiplexing the assay further reduces sample volume requirements, enabling multiple results from a single sample.
Recent improvements by Luminex include: the new MAGPIX system, a smaller, less expensive, easier-to-use analyzer; Low-Concentration Magnetic MagPlex Microspheres which eliminate the need for expensive filter plates and come in a working concentration better suited for assay development and low-throughput applications; and the xMAP Antibody Coupling (AbC) Kit, which includes a protocol, reagents, and consumables necessary for coupling beads to the capture antibody of interest. (See Materials section for a detailed list of kit contents.)
In this experiment, we convert a pre-optimized ELISA assay for TNF-alpha cytokine to the xMAP platform and compare the performance of the two methods 7-11. TNF-alpha is a biomarker used in the measurement of inflammatory responses in patients with autoimmune disorders.
We begin by coupling four candidate capture antibodies to four different microsphere sets or regions. When mixed together, these four sets allow for the simultaneous testing of all four candidates with four separate detection antibodies to determine the best antibody pair, saving reagents, sample and time. Two xMAP assays are then constructed with the two most optimal antibody pairs and their performance is compared to that of the original ELISA assay in regards to signal strength, dynamic range, and sensitivity.

An ELISA can be easily converted to a Luminex xMAP assay and, through the benefits of multiplexing, several antibodies can be screened simultaneously to identify an optimum antibody pair, resulting in increased sensitivity and dynamic range, while reducing assay cost.

转换到一个点阵仪XMAP含量，使用多重抗体筛查方法的捕获ELISA

The enzyme-linked immunosorbent assay (ELISA) has long been the primary tool for detection of analytes of interest in biological samples for both life ...

Quantitative Immunofluorescence Assay to Measure the Variation in Protein Levels at Centrosomes

Centrosomes are small but important organelles that serve as the poles of mitotic spindle to maintain genomic integrity or assemble primary cilia to facilitate sensory functions in cells. The level of a protein may be regulated differently at centrosomes than at other .cellular locations, and the variation in the centrosomal level of several proteins at different points of the cell cycle appears to be crucial for the proper regulation of centriole assembly. We developed a quantitative fluorescence microscopy assay that measures relative changes in the level of a protein at centrosomes in fixed cells from different samples, such as at different phases of the cell cycle or after treatment with various reagents. The principle of this assay lies in measuring the background corrected fluorescent intensity corresponding to a protein at a small region, and normalize that measurement against the same for another protein that does not vary under the chosen experimental condition. Utilizing this assay in combination with BrdU pulse and chase strategy to study unperturbed cell cycles, we have quantitatively validated our recent observation that the centrosomal pool of VDAC3 is regulated at centrosomes during the cell cycle, likely by proteasome-mediated degradation specifically at centrosomes.

Here, a novel quantitative fluorescence assay is developed to measure changes in the level of a protein specifically at centrosomes by normalizing that protein&#8217;s fluorescence intensity to that of an appropriate internal standard.

定量免疫检测，以衡量在中心体的变异蛋白水平

Centrosomes are small but important organelles that serve as the poles of mitotic spindle to maintain genomic integrity or assemble primary cilia to ...

Isolation of Primary Rat Hepatocytes with Multiparameter Perfusion Control

Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure for primary hepatocyte isolation is technically challenging, especially in portal vein cannulation. The procedure is also prone to occasional contamination and variations in perfusion conditions due to difficulties in the assembly, optimization, or maintenance of the perfusion setup. Here, a detailed protocol for an improved two-step collagenase perfusion procedure with multiparameter perfusion control is presented. Primary rat hepatocytes were successfully and reliably isolated by taking the necessary technical precautions at critical steps of the procedure, and by reducing the operational difficulty and mitigating the variability of perfusion parameters through the adoption of a special intravenous catheter, standardized sterile disposable tubing, temperature control, and real-time monitoring and alarm system. The isolated primary rat hepatocytes consistently exhibit high cell viability (85%-95%), yield (2-5 x 108 cells per 200-300 g rat) and functionality (albumin, urea and CYP activity). The procedure was complemented by an integrated perfusion system, which is compact enough to be set up in the laminar flow hood to ensure aseptic operation.

This protocol details the use of a special intravenous catheter, standardized sterile disposable tubing, temperature control complemented by real-time monitoring, and an alarm system for two-step collagenase perfusion procedure to improve the consistency in the viability, yield, and functionality of isolated primary rat hepatocytes.

多参数灌注对照分离原代大鼠肝细胞

Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure ...

Application of Ultrasound and Shear Wave Elastography Imaging in a Rat Model of NAFLD/NASH

Nonalcoholic Steatohepatitis (NASH) is a condition within the spectrum of Non-Alcoholic Fatty Liver Disease (NAFLD), which is characterized by liver fat accumulation (steatosis) and inflammation leading to fibrosis. Preclinical models closely recapitulating human NASH/NAFLD are essential in drug development. While liver biopsy is currently the gold standard for measuring NAFLD/NASH progression and diagnosis in the clinic, in the preclinical space, either collection of whole liver samples at multiple timepoints during a study or biopsy of liver is needed for histological analysis to assess the disease stage.
Conducting a liver biopsy mid-study is an invasive and labor-intensive procedure, and collecting liver samples to assess disease level increases the number of research animals needed for a study. Thus, there is a need for a reliable, translatable, non-invasive imaging biomarker to detect NASH/NAFLD in these preclinical models. Non-invasive ultrasound-based B-mode images and Shear Wave Elastography (SWE) can be used to measure steatosis as well as liver fibrosis. To assess the utility of SWE in preclinical rodent models of NASH, animals were placed on a pro-NASH diet&#160;and underwent non-invasive ultrasound B-mode and shear wave elastography imaging to measure hepatorenal (HR) index and liver elasticity, measuring progression of both liver fat accumulation and tissue stiffness, respectively, at multiple time points over the course of a given NAFLD/NASH study.
The HR index and elasticity numbers were compared to histological markers of steatosis and fibrosis. The results showed strong correlation between the HR index and percentage of Oil Red O (ORO) staining, as well as between elasticity and Picro-Sirius Red (PSR) staining of livers. The strong correlation between classic ex vivo methods and in vivo imaging results provides evidence that shear wave elastography/ultrasound-based imaging can be used to assess disease phenotype and progression in a preclinical model of NAFLD/NASH.

This protocol describes the use of an enhanced ultrasound technique to non-invasively observe and quantify liver tissue changes in rodent models of nonalcoholic fatty liver disease.

在 NAFLD/NASH 的鼠模型中应用超声波和剪切波弹性成像

Nonalcoholic Steatohepatitis (NASH) is a condition within the spectrum of Non-Alcoholic Fatty Liver Disease (NAFLD), which is characterized by liver fat ...

Detection of Plasmodium Sporozoites in Anopheles Mosquitoes using an Enzyme-linked Immunosorbent Assay

Plasmodium sporozoites are the infective stage of malaria parasites that infect humans. The sporozoites residing in the salivary glands of female Anopheles mosquitoes are transmitted to humans via mosquito bites during blood feeding. The presence of sporozoites in the mosquito salivary glands thus defines mosquito infectiousness. To determine whether an Anopheles mosquito carries Plasmodium sporozoites, the enzyme-linked immunosorbent assay (ELISA) method has been the standard tool to detect the Plasmodium circumsporozoite protein (CSP), the major surface protein of the sporozoites. In this method, the head along with the thorax of each mosquito is separated from the abdomen, homogenized, and subjected to a sandwich ELISA to detect the presence of CSP specific to Plasmodium falciparum and each of the two subtypes, VK210 and VK247, of Plasmodium vivax.This method has been used to study malaria transmission, including the seasonal dynamics of mosquito infection and the species of the major malaria vectors in the study sites.

Detection of Plasmodium Sporozoites in Anopheles Mosquitoes using an Enzyme-linked Immunosorbent Assay

This protocol describes a sandwich enzyme-linked immunosorbent assay to detect salivary gland sporozoites in mosquitoes. Using easily available monoclonal antibodies, the method enables cost-effective, high-throughput detection of mosquitoes carrying Plasmodium falciparum or Plasmodium vivax. The method is suitable for malaria transmission research, including vector surveys.