A lyophilized open-source RT-LAMP assay for molecular diagnostics in resource-limited settings

A critical bottleneck for equitable access to population-scale molecular diagnostics is the limited availability of rapid, inexpensive point-of-care tests, especially in low-and middleincome countries. Here, we developed an open-source reverse transcription loop–mediated isothermal amplification (RT-LAMP) molecular assay for pathogen detection. It is based on nonproprietary enzymes, namely, HIV-1 reverse transcriptase, Bst LF DNA polymerase, and UDG BMTU thermolabile uracil-DNA glycosylase. Formulated as liquid or lyophilized reaction mixtures, these reagents enable sensitive colorimetric detection of respiratory samples without the need for prior nucleic acid isolation. We evaluated our lyophilized RT-LAMP assay on clinical samples with suspected COVID-19 infection, demonstrating high sensitivity and 100% specificity compared with the goldstandard RT–qPCR. Reaction performance was unaffected by prolonged storage of lyophilized reagents at ambient or elevated temperatures. As a proof of concept, we evaluated the robustness and ease of use of lyophilized RT-LAMP reaction mixes through independent laboratory testing of COVID-19 samples in Ghana. Overall, our open-source RT-LAMP assay provides a flexible and scalable point-of-care test that can be adapted for rapid detection of various pathogens in resource-limited settings.