Unique Barcoded Primer-Assisted Sample-Specific Pooled Testing (Uni-Pool) for Large-Scale Screening of Viral Pathogens.

ABSTRACT

Pooled testing has been widely adopted recently to facilitate large-scale community testing during the COVID-19 pandemic. This strategy allows to collect and screen multiple specimen samples in a single test, thus immensely saving the assay time and consumable expenses. Nevertheless, when the outcome of a pooled testing is positive, it necessitates repetitive retesting steps for each sample which can pose a serious challenge during a rising infection wave of increasing prevalence. In this work, we develop a unique barcoded primer-assisted sample-specific pooled testing strategy (Uni-Pool) where the key genetic sequences of the viral pathogen in a crude sample are extracted and amplified with concurrent tagging of sample-specific identifiers. This new process improves the existing pooled testing by eliminating the need for retesting and allowing the test results-positive or negative-for all samples in the pool to be revealed by multiplex melting curve analysis right after real-time polymerase chain reaction. It significantly reduces the total assay time for large-scale screening without compromising the specificity and detection sensitivity caused by the sample dilution of pooling. Our method was able to successfully differentiate five samples, positive and negative, in one pool with negligible cross-reactivity among the positive and negative samples. A pooling of 40 simulated samples containing severe acute respiratory syndrome coronavirus-2 pseudovirus of different loads (min 10 copies/µL; max 103 copies/µL) spiked into artificial saliva was demonstrated in eight randomized pools. The outcome of five samples in one pool with a hypothetical infection prevalence of 15% in 40 samples was successfully tested and validated by a typical Dorman-based pooling.