Covid-19 Method passes scrutiny as a Quick Test Alternative

A three-way comparison study on a new reverse-transcription-free (RFT) testing method for Covid-19 carried out by researchers from the University of Birmingham, found that it was just as sensitive, but faster, than both PCR and LAMP tests currently being used in hospital settings. The findings on the Exponential Amplification Reaction (EXPAR) offered support for its potential use at UK entertainment venues, airport and shipping arrival terminals and in other areas where clinical testing laboratories are not available.

Professors Tim Dafforn from the School of Biosciences, and Jim Tucker from the School of Chemistry, worked with graduate student Jake Carter, and Professor Andrew Beggs from the Institute of Cancer and Genomic Sciences on the Birmingham COVID-19 test, called RTF-EXPAR, found to give a sample-to-signal time of under 10 minutes, even for low viral levels where current lateral flow tests are less effective.

“与没有这些步骤的抗原检测(如侧流)相比，逆转录和扩增步骤都减缓了现有的基于核酸检测的COVID检测。然而，虽然这使得横向流动检测比基于PCR和LAMP的检测更快，但它们通常敏感度较低。理想的测试应该是既足够灵敏又足够快速——我们的测试叫做RTF-EXPAR，达到了这个目标。”蒂姆·达丰教授说。

“EXPAR amplifies DNA at a single temperature, thus avoiding lengthy heating and cooling steps found in PCR. However, while LAMP also uses a single temperature for amplification, EXPAR is a simpler and a more direct process, in which much smaller strands are amplified. This makes EXPAR an even faster DNA amplification technique than not only PCR but also LAMP.”

研究表明，RTF-EXPAR方法在10分钟内将不到10条RNA链转化为数十亿份DNA拷贝，使用的是一锅分析，与目前使用的检测方法相比，该方法与更基本的台式设备兼容。

RTF-EXPAR also demonstrated significant improvements over both PCR and LAMP-based assays on time to signal detection.

The assay has been tested at the Surgical Research Laboratory at the University of Birmingham. Professor Andrew Beggs, whose team conducted the testing, commented: “The testing used swabs containing a typical range of viral loads seen during the pandemic, and had a six-minute cut-off time. The analysis showed RTF-EXPAR’s sensitivity is equivalent to quantitative PCR testing, with a positive predictive value of 89%, and a negative predictive value of 93%. We expect to publish the full results of this testing in the near future.”

The team is now seeking commercial partners for rapid licensing, to make the RTF-EXPAR test as available as widely as possible.

使用无逆转录指数扩增反应(RTF-EXPAR)对SARS-CoV-2 RNA进行超快速检测的方法发表在《美国国家科学院院刊》上。

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