A Multiplexed Cas13-Based Assay with Point-of-Care Attributes for Simultaneous COVID-19 Diagnosis and Variant Surveillance

Abstract

Point-of-care (POC) nucleic acid detection technologies are poised to aid gold-standard technologies in controlling the COVID-19 pandemic, yet shortcomings in the capability to perform critically needed complex detection - such as multiplexed detection for viral variant surveillance - may limit their widespread adoption. Herein, we developed a robust multiplexed clustered regularly interspaced short palindromic repeats (CRISPR)-based detection using LwaCas13a and PsmCas13b to simultaneously diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and pinpoint the causative SARS-CoV-2 variant of concern (VOC) - including globally dominant VOCs Delta (B.1.617.2) and Omicron (B.1.1.529) - all the while maintaining high levels of accuracy upon the detection of multiple SARS-CoV-2 gene targets. The platform has several attributes suitable for POC use: premixed, freeze-dried reagents for easy use and storage; convenient direct-to-eye or smartphone-based readouts; and a one-pot variant of the multiplexed detection. To reduce reliance on proprietary reagents and enable sustainable use of such a technology in low- and middle-income countries, we locally produced and formulated our own recombinase polymerase amplification reaction and demonstrated its equivalent efficiency to commercial counterparts. Our tool - CRISPR-based detection for simultaneous COVID-19 diagnosis and variant surveillance that can be locally manufactured - may enable sustainable use of CRISPR diagnostics technologies for COVID-19 and other diseases in POC settings.