{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,12]],"date-time":"2026-04-12T09:02:02Z","timestamp":1775984522503,"version":"3.50.1"},"reference-count":33,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2022,6,25]],"date-time":"2022-06-25T00:00:00Z","timestamp":1656115200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["Project 72545, 02\/SAICT\/2020, FEDER, Portugal2020"],"award-info":[{"award-number":["Project 72545, 02\/SAICT\/2020, FEDER, Portugal2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/05937\/2020"],"award-info":[{"award-number":["UIDB\/05937\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDP\/05937\/2020"],"award-info":[{"award-number":["UIDP\/05937\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>The present work focuses on the detection of SARS-CoV-2 in saliva, contributing to understanding the inhibition effect of the matrix and its influence on the results. Detection of viral genes ORF1ab, N, and E was performed by RT-PCR using saliva directly in the reaction without RNA extraction. Different amounts of saliva were spiked with increasing amounts of viral RNA from COVID-19 patients and subjected to RT-PCR detection. In parallel, 64 saliva samples from confirmed COVID-19 patients were used in two different amounts directly in the RT-PCR reaction and their results compared. The presence of saliva in the RT-PCR always causes a positive shift of the Ct values, but a very high between-person variability of its magnitude was obtained, with increases ranging from 0.93 to 11.36. Viral targets are also affected differently depending on the initial number of viral particles. Due to inhibitors present in saliva, the duplication of sample volume causes only 48 to 61% of the expected Ct value decrease depending on the viral target gene. The use of saliva has advantages, but also limitations, due to potential inhibitors present in the matrix. However, the choice of the target and the right amount of sample may significantly influence the results.<\/jats:p>","DOI":"10.3390\/diagnostics12071547","type":"journal-article","created":{"date-parts":[[2022,6,25]],"date-time":"2022-06-25T10:39:13Z","timestamp":1656153553000},"page":"1547","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["The Matrix Effect in the RT-PCR Detection of SARS-CoV-2 Using Saliva without RNA Extraction"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9484-3233","authenticated-orcid":false,"given":"Orlando","family":"Morais","sequence":"first","affiliation":[{"name":"Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Manuel Rui","family":"Alves","sequence":"additional","affiliation":[{"name":"Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"},{"name":"CISAS, Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6760-304X","authenticated-orcid":false,"given":"Carla","family":"Ramos","sequence":"additional","affiliation":[{"name":"Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fernando","family":"Ferreira","sequence":"additional","affiliation":[{"name":"ACES C\u00e1vado III Barcelos\/Esposende, Rua Dr. Abel Varzim, 4750-253 Barcelos, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3148-4445","authenticated-orcid":false,"given":"Paulo","family":"Fernandes","sequence":"additional","affiliation":[{"name":"Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"},{"name":"CISAS, Escola Superior de Tecnologia e Gest\u00e3o, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"372","DOI":"10.1016\/j.cmi.2018.06.009","article-title":"Saliva as a diagnostic specimen for testing respiratory virus by a point-of-care molecular assay: A diagnostic validity study","volume":"25","author":"To","year":"2019","journal-title":"Clin. 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