LAMP: cheaper, faster, simpler testing for a range of diseases
LAMP is emerging as a new technology which permits faster, cheaper diagnostic testing for a range of diseases.
LAMP is short for loop-mediated isothermal amplification. It’s a single-tube technique for amplifying DNA and, when used for disease detection, is cheaper than standard methods, which makes it suitable when large-scale testing is required. LAMP testing can also be done almost anywhere—not necessarily just in a lab.
Typically, tests to detect the presence of viral RNA rely on reverse transcriptase polymerase chain reaction (RT-PCR) technology, which uses enzymes to convert viral RNA into DNA then then makes copies of that DNA for detection. RT-PCR works well, but not just anyone can do it—highly skilled technicians are usually tasked with the job, and they do it at centralized facilities.
Recently, new products have popped on to the market which simplify the testing process; for example, Mesa Biotech’s Accula is a handheld device into which a technician inserts a slim cartridge containing a sample; the device costs around $300, the cartridges cost about $20 each, and results are available in about a half-hour.
LAMP technology takes testing simplicity a step further, however. New diagnostic machines, like Talis Biomedical’s Talis One, can provide molecular testing in less than 30 minutes and upload results to the cloud. The Talis One’s setup is similar to the Accula, except the machine uses reverse-transcription LAMP (RT-LAMP), which operates at a constant temperature of 65 degrees C, which means the equipment overall is much simpler.
RT-LAMP is an emerging technology which uses auto-cycling strand displacement DNA synthesis as its basis. The reaction requires a polymerase that has high strand displacement activity, and two primers. It’s not close to replacing RT-qPCR, which is still the gold standard in this field, but LAMP is evolving into a good alternative for rapid testing.
LAMP was developed in Japan and first described in a 2000 paper in Nucleic Acids Research by Notomi, et al.
“LAMP is simple and easy to perform once the appropriate primers are prepared, requiring only four primers, a DNA polymerase and a regular laboratory water bath or heat block for reaction,” the authors wrote. “By combination with reverse transcription, LAMP can amplify RNA sequences with high efficiency.”
In that original research, authors amplified a few copies of DNA to 1 billion copies in less than an hour at a single temperature and with more specificity.
“RT-LAMP can achieve high specificity due to the target sequences. Unlike other technologies, RT-LAMP recognizes the target sequence using six independent sequences at the start and by four independent sequences towards the latter stages,” reports Life Sciences News Medical. “Primer recognition of the target genome leads to a strong colorimetric reaction, which allows for detection without highly specialized or costly instrumentation. Similar methods rely on the turbidity of the sample, which increases with the amount of genetic material, to measure viral content. Amplification and detection can also be done by agarose gel analysis.”
So far, RT-LAMP has been used to combat the hepatitis B and West Nile viruses, among others. It’s also been put to work when more sensitivity is needed, as RT-LAMP is ten times more sensitive than normal RT-PCR assays and does not produce false-positive results. A 2014 study described the use of LAMP and microwave irradiation for the quick and reliable molecular detection of malarial parasites.
In the case of West Nile, the authors of one research study in the Journal of Clinical Microbiology stated that the RT-LAMP assay was “extremely rapid, cost-effective, highly sensitive, and specific and has potential usefulness for rapid, comprehensive WN virus surveillance along with virus isolation and/or serology.”
In the case of malaria, researchers using basic lab equipment were able to extract DNA from fresh blood samples as well as samples that had been stored on filter paper for more than a decade; they described a method that could be performed by almost anyone, and which allowed final results to be assessed visually.
The future of LAMP looks bright (OMG best genetics science pun EVER!!!!), with growth predicted to be strong as cases of infectious diseases rise globally. As just one example of its promise, a head-to-head comparison published in the Journal of Clinical Microbiology in 2014 found LAMP beat both PCR and multiplex PCR in a race to detect Arcobacter, a bacteria with an unusually wide range of habitats.
The overall emphasis on LAMP reflects the general move in medicine to point-of-care diagnostics, especially in instances where quick turnarounds are a big deal.
“The really interesting question is whether the diagnostic giants will follow the early leaders and abandon the relative safety of PCR for a potentially faster but less widespread method as assays are redeveloped and redistributed for near-patient testing,” noted a blog from The Technology Partnership. “Given the obvious advantages and the increasing popularity of LAMP in the research community, it is difficult to see why they would choose not to, since opting for redesigned, faster PCR assays may present a similar regulatory burden.”