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Wagner K, Fox P, Gordon E, Hahn W, Olsen K, Markham A, Buglewicz D, Selemenakis P, Lessard A, Goldstein D, Threatt A, Davis L, Miller-Dawson J, Stockett H, Sanders H, Rugh K, Turner H, Remias M, Williams M, Chavez J, Galindo G, Cialek C, Koch A, Fout A, Fosdick B, Broeckling B, Zabel MD. A multiplexed, paired-pooled droplet digital PCR assay for detection of SARS-CoV-2 in saliva. Sci Rep 2023; 13:3075. [PMID: 36813822 PMCID: PMC9944410 DOI: 10.1038/s41598-023-29858-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 02/11/2023] [Indexed: 02/24/2023] Open
Abstract
In response to the SARS-CoV-2 pandemic, we developed a multiplexed, paired-pool droplet digital PCR (MP4) screening assay. Key features of our assay are the use of minimally processed saliva, 8-sample paired pools, and reverse-transcription droplet digital PCR (RT-ddPCR) targeting the SARS-CoV-2 nucleocapsid gene. The limit of detection was determined to be 2 and 12 copies per µl for individual and pooled samples, respectively. Using the MP4 assay, we routinely processed over 1,000 samples a day with a 24-h turnaround time and over the course of 17 months, screened over 250,000 saliva samples. Modeling studies showed that the efficiency of 8-sample pools was reduced with increased viral prevalence and that this could be mitigated by using 4-sample pools. We also present a strategy for, and modeling data supporting, the creation of a third paired pool as an additional strategy to employ under high viral prevalence.
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Affiliation(s)
- Kaitlyn Wagner
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Phil Fox
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Elizabeth Gordon
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Westen Hahn
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Kenzie Olsen
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Alex Markham
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Dylan Buglewicz
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Platon Selemenakis
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Avery Lessard
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Daniella Goldstein
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Alissa Threatt
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Luke Davis
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Jake Miller-Dawson
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Halie Stockett
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | | | - Kristin Rugh
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Houston Turner
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Michelle Remias
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Maggie Williams
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Jorge Chavez
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Gabriel Galindo
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Charlotte Cialek
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Amanda Koch
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Alex Fout
- Department of Statistics, Colorado State University, Fort Collins, CO, 80523, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Bailey Fosdick
- Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, USA
| | - Bettina Broeckling
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA
- Colorado State University, Fort Collins, CO, 80523, USA
| | - Mark D Zabel
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, USA.
- Colorado State University, Fort Collins, CO, 80523, USA.
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Fagre A, Lewis J, Eckley M, Zhan S, Rocha SM, Sexton NR, Burke B, Geiss B, Peersen O, Bass T, Kading R, Rovnak J, Ebel GD, Tjalkens RB, Aboellail T, Schountz T. SARS-CoV-2 infection, neuropathogenesis and transmission among deer mice: Implications for spillback to New World rodents. PLoS Pathog 2021; 17:e1009585. [PMID: 34010360 PMCID: PMC8168874 DOI: 10.1371/journal.ppat.1009585] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 06/01/2021] [Accepted: 04/24/2021] [Indexed: 12/21/2022] Open
Abstract
Coronavirus disease-19 (COVID-19) emerged in late 2019 in China and rapidly became pandemic. As with other coronaviruses, a preponderance of evidence suggests the virus originated in horseshoe bats (Rhinolophus spp.) and may have infected an intermediate host prior to spillover into humans. A significant concern is that SARS-CoV-2 could become established in secondary reservoir hosts outside of Asia. To assess this potential, we challenged deer mice (Peromyscus maniculatus) with SARS-CoV-2 and found robust virus replication in the upper respiratory tract, lungs and intestines, with detectable viral RNA for up to 21 days in oral swabs and 6 days in lungs. Virus entry into the brain also occurred, likely via gustatory-olfactory-trigeminal pathway with eventual compromise to the blood-brain barrier. Despite this, no conspicuous signs of disease were observed, and no deer mice succumbed to infection. Expression of several innate immune response genes were elevated in the lungs, including IFNα, IFNβ, Cxcl10, Oas2, Tbk1 and Pycard. Elevated CD4 and CD8β expression in the lungs was concomitant with Tbx21, IFNγ and IL-21 expression, suggesting a type I inflammatory immune response. Contact transmission occurred from infected to naive deer mice through two passages, showing sustained natural transmission and localization into the olfactory bulb, recapitulating human neuropathology. In the second deer mouse passage, an insertion of 4 amino acids occurred to fixation in the N-terminal domain of the spike protein that is predicted to form a solvent-accessible loop. Subsequent examination of the source virus from BEI Resources determined the mutation was present at very low levels, demonstrating potent purifying selection for the insert during in vivo passage. Collectively, this work has determined that deer mice are a suitable animal model for the study of SARS-CoV-2 respiratory disease and neuropathogenesis, and that they have the potential to serve as secondary reservoir hosts in North America.
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Affiliation(s)
- Anna Fagre
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Juliette Lewis
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Miles Eckley
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Shijun Zhan
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Savannah M. Rocha
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Nicole R. Sexton
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Bradly Burke
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Brian Geiss
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Olve Peersen
- Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Todd Bass
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Rebekah Kading
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Joel Rovnak
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Gregory D. Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ronald B. Tjalkens
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Tawfik Aboellail
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
| | - Tony Schountz
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins, Colorado, United States of America
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