A rapid point-of-care diagnostic tool developed by researchers from the Broad Institute of MIT and Harvard targets the Ebola and Lassa viruses, deadly and highly transmissible pathogens afflicting parts of Africa.

The assay is a clustered regularly interspaced short palindromic repeats (CRISPR)-based Specific High-sensitivity Enzymatic Reporter unLOCKing (SHERLOCK) platform. Low viral loads in patient samples are detected and indicated with a fluorescent readout or a result on a paper strip. The low-cost test can be tailored to identify specific viruses from certain regions and requires only a simple heat block and basic supplies to operate. Analysis of saliva or urine samples eliminates the need for blood draws in a diagnostic that returns The HandLens mobile phone app reads and reports paper strip SHERLOCK results. Source: Anna Lachenauer et al.results in less than an hour.

SHERLOCK is deployed in conjunction with Heating Unextracted Diagnostic Samples to Obliterate Nucleases (HUDSON), a rapid chemical and heat treatment to inactive the virus in patient samples. HUDSON renders patient samples safer for clinical staff to handle in resource-limited settings and it eliminates the need to extract viral genetic material from samples before analysis.

A Lassa-specific assay was field tested during a recent Lassa fever outbreak in Nigeria, and an Ebola-specific version of the SHERLOCK system was evaluated with samples collected during recent outbreaks in Sierra Leone the Democratic Republic of the Congo. Results published in Nature Communications confirm that SHERLOCK performed as consistently as, or better than, conventionally used diagnostics, indicating its potential for clinical use in areas with limited infrastructure.

A mobile phone app was also engineered to produce a consistent readout free of operator bias as an aid in cases where the paper strip may be difficult to interpret due to a faint signal. The HandLens app can be adapted for use on any smartphone or tablet to quantify test results and resolve ambiguous readouts.