This book focuses on probiotics with antiviral activities. The "antiviral probiotic" is a new concept in medical sciences. Recently, studies have shown that antiviral probiotics can fight or prevent viral infections in many ways. The immunomodulation of mucosal immunity, production of antiviral compounds, virus trapping and the use thereof as vaccination vectors are the principal modes of action of antiviral probiotics. The author dedicates an entire chapter of the book to discussing the methods and techniques used to assess the antiviral activity of probiotic strains and their metabolites