Rapid Molecular Detection of SARS-CoV-2 (COVID-19) Virus RNA Using Colorimetric LAMP

Yinhua Zhang; Nelson Odiwuor; Jin Xiong; Luo Sun; Raphael Ohuru Nyaruaba; Hongping Wei; Nathan A Tanner

This will of course enable maximum efficiency and sensitivity but requires skill and instrumentation in addition to adding extra time to the diagnostic workflow. We investigated whether it is possible to perform detection using crude cell lysate in order to avoid this RNA purification step. The results indicated that ~480 copies were detected with all four primer sets, a similar sensitivity as the detection sensitivity with synthetic RNA alone (Fig. 3A) with no interference by the lysate to either the amplification efficiency or visual color change. We also tested whether we could recover the synthetic RNA spiked into biological sample with a mock experiment during purification of total RNA. We spiked various amount of synthetic RNA into whole human blood and purified the total blood RNA. We were able to recover and detect the spiked RNA (Fig. 3B) , indicating the total RNA has no interference during the purification or the detection process. While the column-based approach is less compatible with the simple, field detection enabled by colorimetric LAMP, this is a typical laboratory workflow and can be used with simple isothermal amplification in a similar fashion to more expensive and involved qPCR detection workflows.