Synbiotic and Probiotic Postbiotics Suppress HSV-1 and VSV Infectivity in Vitro

This study investigated the in vitro antiviral potential of prebiotics, probiotics, and synbiotics against two viral models, Herpes simplex virus type 1 (HSV-1) and vesicular stomatitis virus (VSV), using Vero cell cultures. Lactobacillus strains (L. acidophilus, L. rhamnosus, and L. plantarum) were evaluated as cell-free supernatants, cell sonicates, and synbiotic combinations with selected plant-derived prebiotic extracts. Cytotoxicity was first assessed by MTT to determine safe treatment concentrations, then antiviral activity was quantified by cytopathic effect–based endpoint titration (TCID ₅₀ ) and expressed as percentage reduction in viral infectivity relative to untreated controls. Overall, several preparations decreased HSV-1 and VSV titers, with the strongest activity consistently observed for L. plantarum and L. acidophilus. In particular, L. plantarum cell sonicate and supernatant produced the highest reductions in infectivity (up to 41.66% for HSV-1 and 38.88% for VSV), while selected synbiotic mixtures also showed notable activity. These findings support the concept that probiotic-derived preparations and synbiotic formulations can reduce infectivity of both DNA and RNA virus models in vitro and may represent promising, non-invasive candidates for further development as adjunct antiviral strategies.