Agreement and differential use of laboratory methods for the detection and quantification of SARS-CoV-2 in experimentally infected animals

Carla Usai; Lola Pailler-García; Cristina Lorca-Oró; Leira Fernández-Bastit; Núria Roca; Marco Brustolin; Jordi Rodon; Mónica Pérez; Guillermo Cantero; Jorge Carrillo; Nuria Izquierdo-Useros; Julià Blanco; Bonaventura Clotet; Sebastián Napp; Joaquim Segalés; Júlia Vergara-Alert

doi:10.3389/fmicb.2022.1016201

Agreement and differential use of laboratory methods for the detection and quantification of SARS-CoV-2 in experimentally infected animals

Front Microbiol. 2022 Nov 15:13:1016201. doi: 10.3389/fmicb.2022.1016201. eCollection 2022.

Authors

Carla Usai^{1

2}, Lola Pailler-García^{1

2}, Cristina Lorca-Oró^{1

2}, Leira Fernández-Bastit^{1

2}, Núria Roca^{1

2}, Marco Brustolin^{1

2}, Jordi Rodon^{1

2}, Mónica Pérez^{1

2}, Guillermo Cantero^{1

2}, Jorge Carrillo^{3

4

5}, Nuria Izquierdo-Useros^{3

4

5}, Julià Blanco^{3

4

5

6}, Bonaventura Clotet^{3

6}, Sebastián Napp^{1

2}, Joaquim Segalés^{1

7}, Júlia Vergara-Alert^{1

2}

Affiliations

¹ Unitat Mixta d'Investigació IRTA-UAB en Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona (UAB), Bellaterra, Catalonia, Spain.
² IRTA Programa de Sanitat Animal, Centre de Recerca en Sanitat Animal (CReSA), Campus de la UAB, Bellaterra, Catalonia, Spain.
³ IrsiCaixa AIDS Research Institute, Badalona, Spain.
⁴ Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain.
⁵ CIBERINFEC, ISCIII, Madrid, Spain.
⁶ Infectious Diseases and Immunity, Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), Barcelona, Spain.
⁷ Department de Sanitat i Anatomia Animals, Facultat de Veterinària, Campus de la UAB, Bellaterra, Catalonia, Spain.

Abstract

Rodents are widely used for the development of COVID-19-like animal models, the virological outcome being determined through several laboratory methods reported in the literature. Our objective was to assess the agreement between methods performed on different sample types from 342 rodents experimentally infected with SARS-CoV-2 (289 golden Syrian hamsters and 53 K18-hACE2 mice). Our results showed moderate agreement between methods detecting active viral replication, and that increasing viral loads determined by either RT-qPCR or infectious viral titration corresponded to increasing immunohistochemical scores. The percentage of agreement between methods decreased over experimental time points, and we observed poor agreement between RT-qPCR results and viral titration from oropharyngeal swabs. In conclusion, RT-qPCR and viral titration on tissue homogenates are the most reliable techniques to determine the presence and replication of SARS-CoV-2 in the early and peak phases of infection, and immunohistochemistry is valuable to evaluate viral distribution patterns in the infected tissues.

Keywords: RT-qPCR; agreement; comparison; immunohistochemistry; oropharyngeal swab; severe acute respiratory syndrome coronavirus 2; tissues; virus titration.