Antiviral activity of lambda-carrageenan against influenza viruses and severe acute respiratory syndrome coronavirus 2

Abstract Influenza virus and coronavirus, belonging to enveloped RNA viruses, are major causes of human respiratory diseases. The aim this study was investigate the broad spectrum antiviral activity a naturally existing sulfated polysaccharide, lambda-carrageenan (?-CGN), purified from marine red algae. Cell culture-based assays revealed that macromolecule efficiently inhibited both influenza A B viruses with EC 50 values ranging 0.3 1.4 ?g/ml, as well currently circulating severe acute syndrome coronavirus 2 (SARS-CoV-2) an value 0.9 ± 1.1 ?g/ml. No toxicity host cells observed at concentrations up 300 Plaque titration western blot analysis verified ?-CGN reduced expression viral proteins in cell lysates suppressed progeny production culture supernatants dose-dependent manner. This polyanionic compound exerts by targeting attachment surface receptors preventing entry. Moreover, its intranasal administration mice during challenge not only alleviated infection-mediated reductions body weight but also protected 60% virus-induced mortality. Thus, could be promising agent for infection several viruses.