RT-LAMP – A Fast, Sensitive, and Accurate Loop-Mediated Isothermal Amplification Test

If you’re looking for a rapid, sensitive, accurate, versatile diagnostic test, you may consider a loop-mediated isothermal amplification test, or LAMP. These tests work by amplification of genetic material at a constant temperature. Compared with other diagnostic tests, such as PCR, LAMP is both fast and affordable. It can be used to detect and treat disease-causing viruses, bacteria, and parasites.

There are several types of LAMP tests that can be purchased. One type is called Direct RT-LAMP and can be used for routine, interval-based testing. This type of assay has the highest diagnostic sensitivity and specificity on saliva samples. Alternatively, a colorimetric assay has been developed that utilizes a divalent zinc salt to detect the presence of the LAMP product. In addition to providing a more sensitive test, the colorimetric method also reduces the impact of acidic saliva samples.

A comparison of RT-LAMP and RT-qPCR was carried out to determine the performance of these two methods. RT-LAMP has been proven to be more sensitive than RT-qPCR. However, a higher positivity rate was observed with RT-qPCR.

The RT-LAMP assay was also evaluated for positive and negative predictive values. For this purpose, a total of 12,521 saliva samples were tested. Of these, 5,591 were evaluated for sensitivity and a further 4,658 for specificity. Using a conservative criteria for detecting positive cases, two targets were necessary for a positive result. An additional sample, which did not meet this standard, was excluded from analysis.

To examine the RT-LAMP assay’s diagnostic sensitivity, the viral load of each sample was assessed. Medium-high viral loads are the most relevant to a virus transmission. Low-to-medium viral loads are generally non-relevant to a virus infection. RT-LAMP showed decreased sensitivity for low viral loads and increased sensitivity for medium-high viral loads.

Using a colorimetric assay, a greater specificity for a medium-high viral load was observed with RT-LAMP. Moreover, the new colorimetric reading used a complexometric indicator to detect the LAMP product. When used with crude samples, the new reading can be difficult to distinguish with the naked eye. Nevertheless, this method has been shown to be useful in determining the presence of the target gene.

Among RT-LAMP assays, direct RT-LAMP is the most sensitive and specific for detecting infectious cases. On the other hand, the OptiGene RT-LAMP assay has been proven to be effective in identifying people who are not infected. As an index test, the OptiGene RT-LAMP test has a 79% sensitivity and a 100% specificity.

RT-LAMP assays are not only easy to perform, they also provide a more cost-effective means of detecting SARS-CoV-2. This approach is particularly suitable for resource-limited settings. Unlike PCR, RT-LAMP assays are easier to scale up and can be incorporated into a mobile testing unit. They also have the potential to be used in high-throughput screening.

Ultimately, RT-LAMP has the potential to become an important point-of-care test for SARS-CoV-2. Nonetheless, it has not yet been tested for its diagnostic accuracy in a real-life clinical setting.