{"doi":"10.1093/clinchem/hvaa267","title":"Rapid and Extraction-Free Detection of SARS-CoV-2 from Saliva by Colorimetric Reverse-Transcription Loop-Mediated Isothermal Amplification","abstract":"BACKGROUND: Rapid, reliable, and widespread testing is required to curtail the ongoing COVID-19 pandemic. Current gold-standard nucleic acid tests are hampered by supply shortages in critical reagents including nasal swabs, RNA extraction kits, personal protective equipment, instrumentation, and labor. METHODS: To overcome these challenges, we developed a rapid colorimetric assay using reverse-transcription loop-mediated isothermal amplification (RT-LAMP) optimized on human saliva samples without an RNA purification step. We describe the optimization of saliva pretreatment protocols to enable analytically sensitive viral detection by RT-LAMP. We optimized the RT-LAMP reaction conditions and implemented high-throughput unbiased methods for assay interpretation. We tested whether saliva pretreatment could also enable viral detection by conventional reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Finally, we validated these assays on clinical samples. RESULTS: The optimized saliva pretreatment protocol enabled analytically sensitive extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP or RT-qPCR. In simulated samples, the optimized RT-LAMP assay had a limit of detection of 59 (95% confidence interval: 44-104) particle copies per reaction. We highlighted the flexibility of LAMP assay implementation using 3 readouts: naked-eye colorimetry, spectrophotometry, and real-time fluorescence. In a set of 30 clinical saliva samples, colorimetric RT-LAMP and RT-qPCR assays performed directly on pretreated saliva samples without RNA extraction had accuracies greater than 90%. CONCLUSIONS: Rapid and extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP is a simple, sensitive, and cost-effective approach with broad potential to expand diagnostic testing for the virus causing COVID-19.","journal":"Clinical Chemistry","year":2020,"id":49625,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":243,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9558,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":243597,"name":"Joshua S Langmade","orcid":null,"position":1,"is_corresponding":false},{"id":240469,"name":"Xuhua Chen","orcid":"0009-0006-9159-7624","position":2,"is_corresponding":false},{"id":109973,"name":"Catrina C. Fronick","orcid":"0000-0002-2766-9551","position":3,"is_corresponding":false},{"id":243598,"name":"Christopher S. Sawyer","orcid":null,"position":4,"is_corresponding":false},{"id":243599,"name":"Lauren C. Burcea","orcid":null,"position":5,"is_corresponding":false},{"id":240470,"name":"Michael Wilkinson","orcid":"0000-0003-3004-6811","position":6,"is_corresponding":false},{"id":1766,"name":"Robert S. Fulton","orcid":"0009-0006-6820-3404","position":7,"is_corresponding":false},{"id":243600,"name":"Michael Heinz","orcid":null,"position":8,"is_corresponding":false},{"id":240471,"name":"William Buchser","orcid":"0000-0002-6675-6359","position":9,"is_corresponding":false},{"id":107158,"name":"Richard D. Head","orcid":"0000-0002-6865-1542","position":10,"is_corresponding":false},{"id":72563,"name":"Robi D. Mitra","orcid":"0000-0002-2680-4264","position":11,"is_corresponding":false},{"id":240472,"name":"Jeffrey Milbrandt","orcid":"0000-0002-5477-7689","position":12,"is_corresponding":false},{"id":240468,"name":"Matthew A. Lalli","orcid":"0000-0003-0419-1206","position":0,"is_corresponding":true}],"reference_count":36,"raw_metadata":null,"created_at":"2026-07-18T20:37:28.027635Z","pmid":"33098427","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}