EPS T14 from Bacillus licheniformis Prevents Infection of Human Nasal Epithelial Cells by Respiratory Viruses

Gaetana Pezzino,1 Alessia Calabrò,1 Fabiana Drommi,1 Stefania Campana,1 Riccardo Cavaliere,1,2 Irene Bonaccorsi,1 Paolo Carrega,1 Vincenzo Zammuto,3– 5 Maria Giovanna Rizzo,3 Concetta Gugliandolo,3,4 Guido Ferlazzo,6,7 Claudia De Pasquale1 1Laboratory of Immunology and Biotherapy, Department Human Pathology ”G. Barresi”, University of Messina, Messina, Italy; 2Division of Clinical Pathology, University Hospital Policlinico G. Martino, Messina, Italy; 3Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy; 4Research Centre for Extreme Environments and Extremophiles, Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy; 5ATHENA Green Solutions S.r.l., Messina, Italy; 6Department of Experimental Medicine (DIMES), University of Genoa, Genova, Italy; 7Unit of Experimental Pathology and Immunology, IRCCS Ospedale Policlinico San Martino, Genova, ItalyCorrespondence: Guido Ferlazzo, Unit of Experimental Pathology and Immunology, IRCCS Ospedale Policlinico San Martino, Genoa, Italy, Email [email protected]: Respiratory viral infections are a leading cause of severe diseases and mortality; therefore, novel treatments effective for their prevention are highly requested. Here, we identified a broad-spectrum antiviral activity of a natural exopolysaccharide, EPS T14, purified from a marine thermotolerant strain of Bacillus licheniformis strain T14.Methods: The effects on human normal nasal epithelial cells (HNEpCs) following treatment with EPS T14 was evaluated at different time points and with increasing concentration of compound. To assess the antiviral properties, viability of HNEpCs treated with EPS T14 was analysed following infection with different respiratory viruses.Results: Neither toxicity nor pro-inflammatory properties were observed in vitro on HNEpCs treated with EPS T14 up to high concentrations, thus ensuring its safety. Cell culture-based assays revealed that treatment of HNEpCs with EPS T14 (used at 400ug/mL) results in efficient prevention of cell infection by different respiratory viruses through physically hindering the entry of the viruses via cell surface receptors. Interestingly, in addition to this prophylactic antiviral activity, EPS T14 also shows a long-lasting efficacy by inhibiting viral spread in the cell culture. Finally, combination of EPS T14 with a hypertonic saline solution shows a synergistic antiviral activity.Conclusion: EPS T14 can exert both prophylactic and therapeutic antiviral activity by blocking viral attachment to cellular receptors and could therefore represent a promising antiviral agent for preventing infections by different respiratory viruses. Keywords: exopolysaccharides, infection prophylaxis, nasal epithelium, respiratory virus, viral infection, EPSs