Antiviral activity of postbiotics from Bifidobacterium animalis subsp. lactis BB-12 and Lacticaseibacillus rhamnosus GG against SARS-CoV-2: In-vitro and food model evaluation.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has presented ongoing global health, economic, and societal challenges. In addition to respiratory complications, increasing evidence suggests that disruptions to the gut microbiota may influence disease susceptibility and severity, highlighting the importance of microbiome-based interventions in supporting host immunity. While probiotics have been widely explored for their immunomodulatory and antiviral effects, limitations regarding their stability and safety under certain conditions remain a concern. Postbiotics, defined as non-viable microbial metabolites, secreted factors, and ultrasonicated bacterial lysate components, represent a promising alternative due to their enhanced safety profile, stability, and emerging antiviral properties. This study investigated the antiviral efficacy of postbiotics derived from Lacticaseibacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB-12 against SARS-CoV-2 using Vero E6 cells cultures. Furthermore, a novel food-based antiviral model was developed by incorporating postbiotic supernatants and ultrasonicated bacterial lysate at a concentration of 1500 μg/mL into a yogurt matrix. The postbiotic-enriched yogurt achieved a 1.87-2.48 log₁₀ reduction in viral titer against the Wuhan strain of SARS-CoV-2 in vitro. These findings support the potential of postbiotics as functional food ingredients for viral risk reduction and contribute to the advancement of microbiome-derived antiviral strategies.