COVID-eVax, an electroporated DNA vaccine candidate encoding the SARS-CoV-2 RBD, elicits protective responses in animal models

Antonella Conforti, Emanuele Marra, Fabio Palombo, Giuseppe Roscilli, Micol Ravà, Valeria Fumagalli, Alessia Muzi, Mariano Maffei, Laura Luberto, Lucia Lione, Erika Salvatori, Mirco Compagnone, Eleonora Pinto, Emiliano Pavoni, Federica Bucci, Grazia Vitagliano, Daniela Stoppoloni, Maria Lucrezia Pacello, Manuela Cappelletti, Fabiana Fosca FerraraEmanuela D'Acunto, Valerio Chiarini, Roberto Arriga, Abraham Nyska, Pietro Di Lucia, Davide Marotta, Elisa Bono, Leonardo Giustini, Eleonora Sala, Chiara Perucchini, Jemma Paterson, Kathryn Ann Ryan, Amy Rose Challis, Giulia Matusali, Francesca Colavita, Gianfranco Caselli, Elena Criscuolo, Nicola Clementi, Nicasio Mancini, Rüdiger Groß, Alina Seidel, Lukas Wettstein, Jan Münch, Lorena Donnici, Matteo Conti, Raffaele De Francesco, Mirela Kuka, Gennaro Ciliberto, Concetta Castilletti, Maria Rosaria Capobianchi, Giuseppe Ippolito, Luca G. Guidotti, Lucio Rovati, Matteo Iannacone*, Luigi Aurisicchio

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The COVID-19 pandemic caused by SARS-CoV-2 has made the development of safe and effective vaccines a critical priority. To date, four vaccines have been approved by European and American authorities for preventing COVID-19, but the development of additional vaccine platforms with improved supply and logistics profiles remains a pressing need. Here we report the preclinical evaluation of a novel COVID-19 vaccine candidate based on the electroporation of engineered, synthetic cDNA encoding a viral antigen in the skeletal muscle. We constructed a set of prototype DNA vaccines expressing various forms of the SARS-CoV-2 spike (S) protein and assessed their immunogenicity in animal models. Among them, COVID-eVax—a DNA plasmid encoding a secreted monomeric form of SARS-CoV-2 S protein receptor-binding domain (RBD)—induced the most potent anti-SARS-CoV-2 neutralizing antibody responses (including against the current most common variants of concern) and a robust T cell response. Upon challenge with SARS-CoV-2, immunized K18-hACE2 transgenic mice showed reduced weight loss, improved pulmonary function, and lower viral replication in the lungs and brain. COVID-eVax conferred significant protection to ferrets upon SARS-CoV-2 challenge. In summary, this study identifies COVID-eVax as an ideal COVID-19 vaccine candidate suitable for clinical development. Accordingly, a combined phase I-II trial has recently started.

Original languageEnglish
Pages (from-to)311-326
Number of pages16
JournalMolecular Therapy
Issue number1
Publication statusPublished - 5 Jan 2022

Bibliographical note

Funding Information: We thank the entire Rottapharm Biotech and IGEA Teams for useful scientific and regulatory discussions and for setting up the EPSGun technology in a short time. We also thank M. Mainetti, M. Freschi, and A. Fiocchi for technical support; M. Silva for secretarial assistance; and the members of the Iannacone laboratory for helpful discussions. Flow cytometry was carried out at FRACTAL, a flow cytometry resource and advanced cytometry technical applications laboratory established by the San Raffaele Scientific Institute. Confocal immunofluorescence histology was carried out at Alembic, an advanced microscopy laboratory established by the San Raffaele Scientific Institute and the Vita-Salute San Raffaele University. We would like to acknowledge the PhD program in Basic and Applied Immunology and Oncology at Vita-Salute San Raffaele University, as D.M. and E. Sala conducted this study as partial fulfillment of their PhD in Molecular Medicine within that program. M.I. is supported by European Research Council ( ERC ) Consolidator Grant 725038 , ERC Proof of Concept Grant 957502 , Italian Association for Cancer Research ( AIRC ) Grants 19891 and 22737 , Italian Ministry of Health Grants RF-2018-12365801 and COVID-2020-12371617 , Lombardy Foundation for Biomedical Research (FRRB) Grant 2015-0010 , the European Molecular Biology Organization Young Investigator Program , and Funded Research Agreements from Gilead Sciences , Takis Biotech , Toscana Life Sciences , and Asher Bio . L.G.G. is supported by AIRC Grant 22737 , Lombardy Open Innovation Grant 229452 , PRIN Grant 2017MPCWPY from the Italian Ministry of Education, University and Research , Funded Research Agreements from Gilead Sciences , Avalia Therapeutics , and CNCCS SCARL , and donations from FONDAZIONE SAME and FONDAZIONE PROSSIMO MIO for COVID-19-related research. M.K. is supported by Italian Ministry of Education, University and Research grant PRIN-2017ZXT5WR . J.M. is supported by funding from the Deutsche Forschungsgemeinschaft through Fokus-Förderung COVID-19 and the CRC1279, the European Union Horizon 2020 Framework Programme for Innovation and Research (Fight-nCoV), the Ministry for Science, Research and Arts of Baden-Württemberg , and the BMWi–Federal Ministry for Economic Affairs and Energy (COMBI-COV-2). R.G., A.S., and L.W. are part of the International Graduate School in Molecular Medicine Ulm. Takis Research activities are supported in part by the Italian Ministry of Economic Development through grants F/050298/02/X32 , F/090033/01-04/X36 , and F/190180/01/X44 . We are also grateful to Lazio Innova for the funding provided through grant A0376-2020-0700050 Prog. T0002E0001 “Emergenza Coronavirus ed oltre” to Vitares no profit organization, and Fondazione Melanoma for providing support to develop the assays used in clinical trials. PHE activities (Covivax project) are supported by the European Network of vaccine research and development ( TRANSVAC2 ).

A.C. and M.M. are Evvivax employees. E.M. F.P. G.R. A.M. L.L. L.L. E. Salvatori, M. Cappalletti, F.F.F. E.D. V.C. and L.A. are Takis employees. G. Caselli and L.R. are Rottapharm Biotech employees. Takis and Rottapharm Biotech are jointly developing COVID-eVax. M.I. participates in advisory boards/consultancies for or receives funding from Gilead Sciences, Roche, Third Rock Ventures, Amgen, Allovir, Asher Bio. L.G.G is a member of the board of directors at Genenta Science and Epsilon Bio and participates in advisory boards/consultancies for Gilead Sciences, Roche, and Arbutus Biopharma.

Open Access: Free to read, but no Open Access licence.

Publisher Copyright: © 2021 The American Society of Gene and Cell Therapy.

Citation: Conforti, Antonella, et al. "COVID-eVax, an electroporated DNA vaccine candidate encoding the SARS-CoV-2 RBD, elicits protective responses in animal models." Molecular Therapy 30.1 (2022): 311-326.



  • DNA vaccine
  • SARS-CoV-2
  • animal models
  • antiviral immunity
  • protection


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