{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:15:18Z","timestamp":1787030118745,"version":"build-2736575974"},"reference-count":28,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,4,2]],"date-time":"2021-04-02T00:00:00Z","timestamp":1617321600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes COVID-19 and is responsible for the ongoing pandemic. Screening of potential antiviral drugs against SARS-CoV-2 depend on in vitro experiments, which are based on the quantification of the virus titer. Here, we used virus-induced cytopathic effects (CPE) in brightfield microscopy of SARS-CoV-2-infected monolayers to quantify the virus titer. Images were classified using deep transfer learning (DTL) that fine-tune the last layers of a pre-trained Resnet18 (ImageNet). To exclude toxic concentrations of potential drugs, the network was expanded to include a toxic score (TOX) that detected cell death (CPETOXnet). With this analytic tool, the inhibitory effects of chloroquine, hydroxychloroquine, remdesivir, and emetine were validated. Taken together we developed a simple method and provided open access implementation to quantify SARS-CoV-2 titers and drug toxicity in experimental settings, which may be adaptable to assays with other viruses. The quantification of virus titers from brightfield images could accelerate the experimental approach for antiviral testing.<\/jats:p>","DOI":"10.3390\/v13040610","type":"journal-article","created":{"date-parts":[[2021,4,2]],"date-time":"2021-04-02T10:34:09Z","timestamp":1617359649000},"page":"610","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Deep Transfer Learning Approach for Automatic Recognition of Drug Toxicity and Inhibition of SARS-CoV-2"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7407-8490","authenticated-orcid":false,"given":"Julia","family":"Werner","sequence":"first","affiliation":[{"name":"Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5444-0189","authenticated-orcid":false,"given":"Raphael M.","family":"Kronberg","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"},{"name":"Mathematical Modelling of Biological Systems, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pawel","family":"Stachura","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4419-6119","authenticated-orcid":false,"given":"Philipp N.","family":"Ostermann","sequence":"additional","affiliation":[{"name":"Institute of Virology, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lisa","family":"M\u00fcller","sequence":"additional","affiliation":[{"name":"Institute of Virology, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1636-4365","authenticated-orcid":false,"given":"Heiner","family":"Schaal","sequence":"additional","affiliation":[{"name":"Institute of Virology, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sanil","family":"Bhatia","sequence":"additional","affiliation":[{"name":"Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Center of Child and Adolescent Health, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3730-5348","authenticated-orcid":false,"given":"Jakob N.","family":"Kather","sequence":"additional","affiliation":[{"name":"Department of Medicine III, University Hospital RWTH Aachen, 52074 Aachen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arndt","family":"Borkhardt","sequence":"additional","affiliation":[{"name":"Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Center of Child and Adolescent Health, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aleksandra A.","family":"Pandyra","sequence":"additional","affiliation":[{"name":"Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Center of Child and Adolescent Health, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karl S.","family":"Lang","sequence":"additional","affiliation":[{"name":"Institute of Immunology, Medical Faculty, University of Duisburg-Essen, 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Philipp A.","family":"Lang","sequence":"additional","affiliation":[{"name":"Department of Molecular Medicine II, Medical Faculty, Heinrich-Heine-University, 40225 D\u00fcsseldorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"853","DOI":"10.1016\/S2213-2600(20)30316-7","article-title":"Case characteristics, resource use, and outcomes of 10 021 patients with COVID-19 admitted to 920 German hospitals: An observational study","volume":"8","author":"Karagiannidis","year":"2020","journal-title":"Lancet Respir. 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