K5 polysaccharides inhibit SARS-CoV-2 infection by preventing spike-proteolytic priming
SARS-CoV-2 spike glycoprotein is a promising drug target due to its crucial role in viral infection. Heparin, a long linear polysaccharide that inhibits SARS-CoV-2 infection by acting on spike, has limited antiviral applications due to its anticoagulant effect. E. coli K5 polysaccharides share the same structure as the heparin precursor and can be chemically modified to be devoid of anticoagulant activity. Here, biochemical assays and computer simulations reveal that K5 with high degree of sulfation at O- (K5OSH) or N- and O-positions (K5NOSH) bind spike with higher affinity than heparin, preventing its binding to ACE2 and furin cleavage. This mechanism is supported by cell syncytia assays showing that K5OSH and K5NOSH inhibit viral infection by blocking membrane fusion. Infection assays for SARS-CoV-2 Wuhan-Hu-1 and Omicron BA.1 variants corroborate their antiviral activity. These results support the therapeutic potential of K5OSH and K5NOSH against SARS-CoV-2, with K5OSH displaying more promising activity profile.
Authors
- Alberto Zani (ORCID: https://orcid.org/0000-0001-9066-7973)
- Rebecca C. Wade (ORCID: https://orcid.org/0000-0001-5951-8670)
- Giulia Paiardi (ORCID: https://orcid.org/0000-0001-6000-0270)
- Maria Milanesi (ORCID: https://orcid.org/0000-0002-1902-1544)
- Marco Rusnati (ORCID: https://orcid.org/0000-0001-9968-5908)
- Liv Zimmermann (ORCID: https://orcid.org/0000-0003-0651-8460)
- Vibor Laketa (ORCID: https://orcid.org/0000-0002-9472-2738)
- Chiara Urbinati (ORCID: https://orcid.org/0000-0002-0138-7871)
- Francesca Caccuri
- Petr Chlanda
- Arnaldo Caruso
- Pasqua Oreste
Institutions
- University of Milan (IT)
- Heidelberg University (DE)
- University Hospital Heidelberg (DE)
- German Center for Infection Research (DE)
- Consorzio Interuniversitario per le Biotecnologie (IT)
- DKFZ-ZMBH Alliance (DE)
- Heidelberg Institute for Theoretical Studies (DE)
- University of Brescia (IT)
- Heidelberg University (US)
Publication Details
- Journal
- npj Viruses
- Published
- 2026-01-09
- DOI
- https://doi.org/10.1038/s44298-025-00163-4
- Primary Topic
- SARS-CoV-2 and COVID-19 Research
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Joachim Herz Stiftung
- Deutsches Zentrum für Infektionsforschung
- European Commission
- Deutsche Forschungsgemeinschaft
- Ministero dell’Istruzione, dell’Università e della Ricerca
- Klaus Tschira Stiftung